Minimum Allowed Quantization For Transform Skip Blocks In Video Coding

ABSTRACT

A method of video processing includes performing a conversion between a video including a video region and a bitstream of the video according to a rule. The rule specifies a relationship between enablement of a palette mode and a coding type of the video region. The video region may represent a coding block of the video.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Patent ApplicationNo. PCT/CN2021/086522 filed on Apr. 12, 2021, which claims the priorityto and benefits of International Patent Application No.PCT/CN2020/084291, filed on Apr. 10, 2020. All the aforementioned patentapplications are hereby incorporated by reference in their entireties.

TECHNICAL FIELD

The present disclosure is related to video and image coding and decodingtechnologies.

BACKGROUND

Digital video accounts for the largest bandwidth use on the internet andother digital communication networks. As the number of connected userdevices capable of receiving and displaying video increases, it isexpected that the bandwidth demand for digital video usage will continueto grow.

SUMMARY

The disclosed techniques may be used by video or image decoder orencoder embodiments for in which reference pictures are used in videocoding or decoding.

In one example aspect a method of video processing is disclosed. Themethod includes parsing, for a conversion between a video region of avideo and a coded representation of the video region, the codedrepresentation according to a syntax rule that defines a relationshipbetween a chroma block size and a color format of the video region andperforming the conversion by performing the parsing according to thesyntax rule.

In another example aspect, another method of video processing isdisclosed. The method includes determining, based on a property of avideo and a chroma format of the video, a coding mode of a coding treenode of the video and performing a conversion between a codedrepresentation of the video and a video block of the coding tree nodeusing the determined coding mode.

In yet another example aspect, another method of video processing isdisclosed. The method includes determining, based on a rule, whether acertain size of chroma blocks is allowed in a video region of a videoand performing a conversion between the video region and a codedrepresentation of the video region based on the determining.

In yet another example aspect, another method of video processing isdisclosed. The method includes determining, based on a rule that allowsuse of a coding mode for a video condition, that a coding mode ispermitted for a video region and performing a conversion between a codedrepresentation of pixels in the video region and pixels of the videoregion based on the determining.

In yet another example aspect, another method of video processing isdisclosed. The method includes performing a conversion between a videoblock of a video and a coded representation of the video block using avideo coding mode, wherein a syntax element signaling the coding mode isselectively included in the coded representation based on a rule.

In yet another example aspect, another method of video processing isdisclosed. The method includes determining, due to a chroma block havinga size less than a threshold size, that a transform type used during aconversion between the chroma block and a coded representation of thechroma block is different from a transform type used for a correspondingluma block conversion and performing the conversion based on thedetermining.

In yet another example aspect, another method of video processing isdisclosed. The method includes determining, whether a smallest chromablock rule is enforced during a conversion between a codedrepresentation of a video region and pixel values of the video region,based on a coding condition of the video region; and performing theconversion based on the determining.

In yet another example aspect, another method of video processing isdisclosed. The method includes determining, for a conversion between acoded representation of a video region in a 4:2:2 format and pixelvalues of the video region, a mode type to be used for the conversionbased on whether a smallest chroma block rule is enabled for the videoregion; and performing the conversion based on the determining.

In yet another example aspect, another method of video processing isdisclosed. The method includes determining, for a conversion between acoded representation of a video block and a video block of a video,whether block partitioning is allowed during the conversion, based on amode type used during the conversion or a dimension of the video block;and performing the conversion using the determining.

In yet another example aspect, another method of video processing isdisclosed. The method includes determining, for a conversion between acoded representation of a video segment of a video and the videosegment, to apply a special processing mode for a chroma block of sizeM×N, where M by N are integers; and performing the conversion based onthe determining.

In another example aspect, another method of video processing isdisclosed. The method includes performing a conversion between a videoincluding a video region and a bitstream of the video according to arule; and wherein the rule specifies a relationship between enablementof a palette mode and a coding type of the video region.

In another example aspect, another method of video processing isdisclosed. The method includes performing a conversion between a videoincluding a first video region and a second video region and a bitstreamof the video according to a rule; and wherein the rule specifies that aboundary strength (bs) of a deblocking filter for chroma components ofthe video is set to 0 in case that a first block is in an intra blockcopy mode and a second block is in a palette mode.

In another example aspect, another method of video processing isdisclosed. The method includes performing a conversion between a videoand a bitstream of the video according to a format rule, and wherein theformat rule specifies that a variable related to an input bit depth ofthe video is constrained according to a profile of the bitstream.

In another example aspect, another method of video processing isdisclosed. The method includes performing a conversion between a videoand a bitstream of the video according to a format rule, and wherein theformat rule specifies that a variable indicating minimum allowedquantization parameter is constrained according to a profile of thebitstream.

In yet another example aspect, the above-described method may beimplemented by a video encoder apparatus that comprises a processor.

In yet another example aspect, the above-described method may beimplemented by a video decoder apparatus that comprises a processor.

In yet another example aspect, these methods may be embodied in the formof processor-executable instructions and stored on a computer-readableprogram medium.

These, and other, aspects are further described in the presentdisclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an example of intra block copy coding tool.

FIG. 2 shows an example of a block coded in palette mode.

FIG. 3 shows an example of use of palette predictor to signal paletteentries.

FIG. 4 shows an example of examples of Horizontal and vertical traversescans.

FIG. 5 shows examples of coding of palette indices.

FIG. 6 shows an example of 67 intra prediction modes.

FIG. 7 shows examples of the left and above neighbors of the currentblock.

FIG. 8 shows examples of adaptive loop filter (ALF) filter shapes(chroma: 5×5 diamond, luma: 7×7 diamond).

FIG. 9 shows an example of subsampled Laplacian calculation.

FIG. 10 shows an example of a modified block classification at virtualboundaries.

FIG. 11 is an example illustration of modified ALF filtering for lumacomponent at virtual boundaries.

FIG. 12 shows examples of four one dimensional (1-D) 3-pixel patternsfor the pixel classification in edge offset (EO).

FIG. 13 four bands are grouped together and represented by its startingband position.

FIG. 14 top and left neighboring blocks used in Combined Inter-IntraPrediction (CIIP) weight derivation.

FIG. 15 shows luma mapping with chroma scaling architecture.

FIG. 16 shows examples of smallest chroma intra prediction unit (SCIPU).

FIGS. 17A and 17B show block diagrams of examples of a hardware platformused for implementing techniques described in the present disclosure.

FIG. 18 is a flowchart for an example method of video processing.

FIG. 19 shows examples of positions of spatial merge candidates.

FIG. 20 shows examples of candidate pairs considered for redundancycheck of spatial merge candidates.

FIG. 21 is a block diagram that illustrates an example video codingsystem.

FIG. 22 is a block diagram that illustrates an encoder in accordancewith some embodiments of the disclosed technology.

FIG. 23 is a block diagram that illustrates a decoder in accordance withsome embodiments of the disclosed technology.

FIGS. 24A to 24D are flowcharts for example methods of video processingin accordance with some embodiments of the disclosed technology.

DETAILED DESCRIPTION

The present disclosure provides various techniques that can be used by adecoder of image or video bitstreams to improve the quality ofdecompressed or decoded digital video or images. For brevity, the term“video” is used herein to include both a sequence of pictures(traditionally called video) and individual images. Furthermore, a videoencoder may also implement these techniques during the process ofencoding in order to reconstruct decoded frames used for furtherencoding.

Section headings are used in the present disclosure for ease ofunderstanding and do not limit the embodiments and techniques to thecorresponding sections. As such, embodiments from one section can becombined with embodiments from other sections.

1. BRIEF SUMMARY

This disclosure is related to video coding technologies. Specifically,it is related to palette coding with employing base colors basedrepresentation in video coding. It may be applied to the existing videocoding standard like High Efficiency Video Coding (HEVC), or thestandard Versatile Video Coding (VVC) to be finalized. It may be alsoapplicable to future video coding standards or video codec.

2. INITIAL DISCUSSION

Video coding standards have evolved primarily through the development ofthe well-known International Telecommunication Union-TelecommunicationStandardization Sector (ITU-T) and International Organization forStandardization (ISO)/International Electrotechnical Commission (IEC)standards. The ITU-T produced H.261 and H.263, ISO/IEC produced MovingPicture Experts Group (MPEG)-1 and MPEG-4 Visual, and the twoorganizations jointly produced the H.262/MPEG-2 Video and H.264/MPEG-4Advanced Video Coding (AVC) and H.265/HEVC standards. Since H.262, thevideo coding standards are based on the hybrid video coding structurewherein temporal prediction plus transform coding are utilized. Toexplore the future video coding technologies beyond HEVC, Joint VideoExploration Team (JVET) was founded by Video Coding Experts Group (VCEG)and MPEG jointly in 2015. Since then, many new methods have been adoptedby JVET and put into the reference software named Joint ExplorationModel (JEM). In April 2018, the Joint Video Expert Team (JVET) betweenVCEG (Q6/16) and ISO/IEC JTC1 SC29/WG11 (MPEG) was created to work onthe VVC standard targeting at 50% bitrate reduction compared to HEVC.

The latest version of VVC draft, i.e., Versatile Video Coding (Draft 4)could be found at:

http://phenix.it-sudparis.eu/jvet/doc_end_user/current_document.php?id=5755

The latest reference software of VVC, named VTM, could be found at:https://vcgit.hhi.fraunhofer.de/jvet/VVCSoftware_VTM/tags/VTM-5.0

2.1 Intra Block Copy

Intra block copy (IBC), a.k.a., current picture referencing, has beenadopted in HEVC Screen Content Coding extensions (HEVC-SCC) and thecurrent VVC test model (VTM-4.0). IBC extends the concept of motioncompensation from inter-frame coding to intra-frame coding. Asdemonstrated in FIG. 1 , the current block is predicted by a referenceblock in the same picture when IBC is applied. The samples in thereference block must have been already reconstructed before the currentblock is coded or decoded. Although IBC is not so efficient for mostcamera-captured sequences, it shows significant coding gains for screencontent. The reason is that there are lots of repeating patterns, suchas icons and text characters in a screen content picture. IBC can removethe redundancy between these repeating patterns effectively. InHEVC-SCC, an inter-coded coding unit (CU) can apply IBC if it choosesthe current picture as its reference picture. The motion vector (MV) isrenamed as block vector (BV) in this case, and a BV always has aninteger-pixel precision. To be compatible with main profile HEVC, thecurrent picture is marked as a “long-term” reference picture in theDecoded Picture Buffer (DPB). It should be noted that similarly, inmultiple view/three dimensional (3D) video coding standards, theinter-view reference picture is also marked as a “long-term” referencepicture.

Following a BV to find its reference block, the prediction can begenerated by copying the reference block. The residual can be got bysubtracting the reference pixels from the original signals. Thentransform and quantization can be applied as in other coding modes.

FIG. 1 is an illustration of intra block copy.

However, when a reference block is outside of the picture, or overlapswith the current block, or outside of the reconstructed area, or outsideof the valid area restricted by some constrains, part or all pixelvalues are not defined. Basically, there are two solutions to handlesuch a problem. One is to disallow such a situation, e.g. in bitstreamconformance. The other is to apply padding for those undefined pixelvalues. The following sub-sessions describe the solutions in detail.

2.2 IBC in HEVC Screen Content Coding Extensions

In the screen content coding extensions of HEVC, when a block usescurrent picture as reference, it should guarantee that the wholereference block is within the available reconstructed area, as indicatedin the following spec text:

The variables offsetX and offsetY are derived as follows:  offsetX = (ChromaArrayType = = 0 ) ? 0 : ( mvCLX[ 0 ] & 0x7 ? 2 : 0 ) (8-104) offsetY = ( ChromaArrayType = = 0 ) ? 0 : ( mvCLX[ 1 ] & 0x7 ? 2 : 0 )(8-105) It is a requirement of bitstream conformance that when thereference picture is the current picture, the luma motion vector mvLXshall obey the following constraints: - When the derivation process forz-scan order block availability as specified in clause 6.4.1 is invokedwith ( xCurr, yCurr ) set equal to ( xCb, yCb ) and the neighbouringluma location ( xNbY, yNbY ) set equal to ( xPb + ( mvLX[ 0 ] >> 2 ) −offsetX, yPb + ( mvLX[ 1 ] >> 2 ) − offsetY ) as inputs, the outputshall be equal to TRUE. - When the derivation process for z-scan orderblock availability as specified in clause 6.4.1 is invoked with ( xCurr,yCurr ) set equal to ( xCb, yCb ) and the neighbouring luma location (xNbY, yNbY ) set equal to ( xPb + ( mvLX[ 0 ] >> 2 ) + nPbW − 1 +offsetX, yPb + ( mvLX[ 1 ] >> 2 ) + nPbH − 1 + offsetY ) as inputs, theoutput shall be equal to TRUE. - One or both of the following conditionsshall be true: - The value of ( mvLX[ 0 ] >> 2 ) + nPbW + xB1 + offsetXis less than or equal to 0. - The value of ( mvLX[ 1 ] >> 2 ) + nPbH +yB1 + offsetY is less than or equal to 0. - The following conditionshall be true:  ( xPb + ( mvLX[ 0 ] >> 2 ) + nPbSw − 1 + offsetX ) /CtbSizeY − xCb / CtbSizeY <=   yCb/CtbSizeY − ( yPb + ( mvLX[ 1 ] >> 2) + nPbSh − 1 + offsetY ) / CtbSizeY (8-106)

Thus, the case that the reference block overlaps with the current blockor the reference block is outside of the picture will not happen. Thereis no need to pad the reference or prediction block.

2.3 IBC in VVC Test Model

In the current VVC test model, i.e. VTM-4.0 design, the whole referenceblock should be with the current coding tree unit (CTU) and does notoverlap with the current block. Thus, there is no need to pad thereference or prediction block. The IBC flag is coded as a predictionmode of the current coding unit (CU). Thus, there are totally threeprediction modes, MODE_INTRA, MODE_INTER and MODE_IBC for each CU.

2.3.1 IBC Merge Mode

In IBC merge mode, an index pointing to an entry in the IBC mergecandidates list is parsed from the bitstream. The construction of theIBC merge list can be summarized according to the following sequence ofsteps:

-   -   Step 1: Derivation of spatial candidates    -   Step 2: Insertion of History-based Motion Vector Prediction        (HMVP) candidates    -   Step 3: Insertion of pairwise average candidates

In the derivation of spatial merge candidates, a maximum of four mergecandidates are selected among candidates located in the positionsdepicted in FIG. 19 . The order of derivation is A₁, B₁, B₀, A₀ and B₂.Position B₂ is considered only when any prediction unit (PU) of positionA₁, B₁, B₀, A₀ is not available (e.g. because it belongs to anotherslice or tile) or is not coded with IBC mode. After candidate atposition A₁ is added, the insertion of the remaining candidates issubject to a redundancy check which ensures that candidates with samemotion information are excluded from the list so that coding efficiencyis improved. To reduce computational complexity, not all possiblecandidate pairs are considered in the mentioned redundancy check.Instead only the pairs linked with an arrow in FIG. 20 are consideredand a candidate is only added to the list if the corresponding candidateused for redundancy check has not the same motion information.

After insertion of the spatial candidates, if the IBC merge list size isstill smaller than the maximum IBC merge list size, IBC candidates fromHMVP table may be inserted. Redundancy check are performed wheninserting the HMVP candidates.

Finally, pairwise average candidates are inserted into the IBC mergelist.

When a reference block identified by a merge candidate is outside of thepicture, or overlaps with the current block, or outside of thereconstructed area, or outside of the valid area restricted by someconstrains, the merge candidate is called invalid merge candidate.

It is noted that invalid merge candidates may be inserted into the IBCmerge list.

2.3.2 IBC AMVP Mode

In IBC advanced motion vector prediction (AMVP) mode, an AMVP indexpoint to an entry in the IBC AMVP list is parsed from the bitstream. Theconstruction of the IBC AMVP list can be summarized according to thefollowing sequence of steps:

-   -   Step 1: Derivation of spatial candidates        -   Check A₀, A₁ until an available candidate is found.        -   Check B₀, B₁, B₂ until an available candidate is found.    -   Step 2: Insertion of HMVP candidates    -   Step 3: Insertion of zero candidates

After insertion of the spatial candidates, if the IBC AMVP list size isstill smaller than the maximum IBC AMVP list size, IBC candidates fromHMVP table may be inserted.

Finally, zero candidates are inserted into the IBC AMVP list.

2.4 Palette Mode

The basic idea behind a palette mode is that the samples in the CU arerepresented by a small set of representative colour values. This set isreferred to as the palette. And it is also possible to indicate a samplethat is outside the palette by signalling an escape symbol followed by(possibly quantized) component values. This kind of sample is calledescape sample. The palette mode is illustrated in FIG. 2 .

FIG. 2 shows an example of a block coded in palette mode.

2.5 Palette Mode in HEVC Screen Content Coding Extensions (HEVC-SCC)

In the palette mode in HEVC-SCC, a predictive way is used to code thepalette and index map.

2.5.1 Coding of the Palette Entries

For coding of the palette entries, a palette predictor is maintained.The maximum size of the palette as well as the palette predictor issignalled in the sequence parameter set (SPS). In HEVC-SCC, apalette_predictor_initializer_present_flag is introduced in the pictureparameter set (PPS). When this flag is 1, entries for initializing thepalette predictor are signalled in the bitstream. The palette predictoris initialized at the beginning of each coding tree unit (CTU) row, eachslice and each tile. Depending on the value of thepalette_predictor_initializer_present_flag, the palette predictor isreset to 0 or initialized using the palette predictor intializer entriessignalled in the PPS. In HEVC-SCC, a palette predictor initializer ofsize 0 was enabled to allow explicit disabling of the palette predictorinitialization at the PPS level.

For each entry in the palette predictor, a reuse flag is signalled toindicate whether it is part of the current palette. This is illustratedin FIG. 3 . The reuse flags are sent using run-length coding of zeros.After this, the number of new palette entries are signalled usingexponential Golomb code of order 0. Finally, the component values forthe new palette entries are signalled.

FIG. 3 shows an example of use of palette predictor to signal paletteentries.

2.5.2 Coding of Palette Indices

The palette indices are coded using horizontal and vertical traversescans as shown in FIG. 4 . The scan order is explicitly signalled in thebitstream using the palette_transpose_flag. For the rest of thesubsection it is assumed that the scan is horizontal.

FIG. 4 shows examples of horizontal and vertical traverse scans.

The palette indices are coded using two main palette sample modes:‘INDEX’ and ‘COPY_ABOVE’. As explained previously, the escape symbol isalso signalled as an ‘INDEX’ mode and assigned an index equal to themaximum palette size. The mode is signalled using a flag except for thetop row or when the previous mode was ‘COPY_ABOVE’. In the ‘COPY_ABOVE’mode, the palette index of the sample in the row above is copied. In the‘INDEX’ mode, the palette index is explicitly signalled. For both‘INDEX’ and ‘COPY_ABOVE’ modes, a run value is signalled which specifiesthe number of subsequent samples that are also coded using the samemode. When escape symbol is part of the run in ‘INDEX’ or ‘COPY_ABOVE’mode, the escape component values are signalled for each escape symbol.The coding of palette indices is illustrated in FIG. 5 .

This syntax order is accomplished as follows. First the number of indexvalues for the CU is signaled. This is followed by signaling of theactual index values for the entire CU using truncated binary coding.Both the number of indices as well as the index values are coded inbypass mode. This groups the index-related bypass bins together. Thenthe palette sample mode (if necessary) and run are signaled in aninterleaved manner. Finally, the component escape values correspondingto the escape samples for the entire CU are grouped together and codedin bypass mode.

An additional syntax element, last_run_type_flag, is signaled aftersignaling the index values. This syntax element, in conjunction with thenumber of indices, eliminates the need to signal the run valuecorresponding to the last run in the block.

In HEVC-SCC, the palette mode is also enabled for 4:2:2, 4:2:0, andmonochrome chroma formats. The signaling of the palette entries andpalette indices is almost identical for all the chroma formats. In caseof non-monochrome formats, each palette entry consists of 3 components.For the monochrome format, each palette entry consists of a singlecomponent. For subsampled chroma directions, the chroma samples areassociated with luma sample indices that are divisible by 2. Afterreconstructing the palette indices for the CU, if a sample has only asingle component associated with it, only the first component of thepalette entry is used. The only difference in signaling is for theescape component values. For each escape sample, the number of escapecomponent values signaled may be different depending on the number ofcomponents associated with that sample.

In VVC, the dual tree coding structure is used on coding the intraslices, so the luma component and two chroma components may havedifferent palette and palette indices. In addition, the two chromacomponent shares same palette and palette indices.

FIG. 5 shows examples of coding of palette indices.

2.6 Intra Mode Coding in VVC

To capture the arbitrary edge directions presented in natural video, thenumber of directional intra modes in VTM5 is extended from 33, as usedin HEVC, to 65. The new directional modes not in HEVC are depicted asdotted arrows in FIG. 6 and the planar and direct current (DC) modesremain the same. These denser directional intra prediction modes applyfor all block sizes and for both luma and chroma intra predictions.

In VTM5, several conventional angular intra prediction modes areadaptively replaced with wide-angle intra prediction modes for thenon-square blocks.

In HEVC, every intra-coded block has a square shape and the length ofeach of its side is a power of 2. Thus, no division operations arerequired to generate an intra-predictor using DC mode. In VTM5, blockscan have a rectangular shape that necessitates the use of a divisionoperation per block in the general case. To avoid division operationsfor DC prediction, only the longer side is used to compute the averagefor non-square blocks.

FIG. 6 shows an example of 67 intra prediction modes.

To keep the complexity of the most probable mode (MPM) list generationlow, an intra mode coding method with 6 MPMs is used by considering twoavailable neighboring intra modes. The following three aspects areconsidered to construct the MPM list:

-   -   Default intra modes    -   Neighbouring intra modes    -   Derived intra modes

A unified 6-MPM list is used for intra blocks irrespective of whethermultiple reference line (MRL) and intra sub-partitions (ISP) codingtools are applied or not. The MPM list is constructed based on intramodes of the left and above neighboring block. Suppose the mode of theleft block is denoted as Left and the mode of the above block is denotedas Above, the unified MPM list is constructed as follows (The left andabove blocks are shown in FIG. 7 ):

FIG. 7 is an example of the left and above neighbors of the currentblock.

-   -   When a neighboring block is not available, its intra mode is set        to Planar by default.    -   If both modes Left and Above are non-angular modes:        -   MPM list→{Planar, DC, V, H, V−4, V+4}    -   If one of modes Left and Above is angular mode, and the other is        non-angular:        -   Set a mode Max as the larger mode in Left and Above        -   MPM list→{Planar, Max, DC, Max−1, Max+1, Max−2}    -   If Left and Above are both angular and they are different:        -   Set a mode Max as the larger mode in Left and Above        -   if the difference of mode Left and Above is in the range of            2 to 62, inclusive            -   MPM list→{Planar, Left, Above, DC, Max−1, Max+1}        -   Otherwise            -   MPM list→{Planar, Left, Above, DC, Max−2, Max+2}    -   If Left and Above are both angular and they are the same:        -   MPM list→{Planar, Left, Left−1, Left+1, DC, Left−2}

Besides, the first bin of the MPM index codeword is context-adaptivebinary arithmetic coding (CABAC) context coded. In total three contextsare used, corresponding to whether the current intra block is MRLenabled, ISP enabled, or a normal intra block.

During 6 MPM list generation process, pruning is used to removeduplicated modes so that only unique modes can be included into the MPMlist. For entropy coding of the 61 non-MPM modes, a Truncated BinaryCode (TBC) is used.

For chroma intra mode coding, a total of 8 intra modes are allowed forchroma intra mode coding. Those modes include five traditional intramodes and three cross-component linear model modes (CCLM, LM_A, andLM_L). Chroma mode signalling and derivation process are shown in Table2-. Chroma mode coding directly depends on the intra prediction mode ofthe corresponding luma block. Since separate block partitioningstructure for luma and chroma components is enabled in I slices, onechroma block may correspond to multiple luma blocks. Therefore, forChroma direct mode (DM), the intra prediction mode of the correspondingluma block covering the center position of the current chroma block isdirectly inherited.

TABLE 2-4 Derivation of chroma prediction mode from luma mode whencclm_is enabled Corresponding luma intra Chroma prediction modeprediction X mode 0 50 18 1 (0 <= X <= 66) 0 66 0 0 0 0 1 50 66 50 50 502 18 18 66 18 18 3 1 1 1 66 1 4 81 81 81 81 81 5 82 82 82 82 82 6 83 8383 83 83 7 0 50 18 1 X

2.7 Quantized Residual Block Differential Pulse-Code Modulation(QR-BDPCM)

In JVET-M0413, a quantized residual block differential pulse-codemodulation (QR-BDPCM) is proposed to code screen contents efficiently.

The prediction directions used in Quantized Residual Block DifferentialPulse Code Modulation (QR-BDPCM) can be vertical and horizontalprediction modes. The intra prediction is done on the entire block bysample copying in prediction direction (horizontal or verticalprediction) similar to intra prediction. The residual is quantized andthe delta between the quantized residual and its predictor (horizontalor vertical) quantized value is coded. This can be described by thefollowing: For a block of size M (rows)×N (cols), let r_(i,j), 0≤i≤M−1,0≤j≤N−1 be the prediction residual after performing intra predictionhorizontally (copying left neighbor pixel value across the predictedblock line by line) or vertically (copying top neighbor line to eachline in the predicted block) using unfiltered samples from above or leftblock boundary samples. Let Q (r_(i,j)), 0≤i≤M−1, 0≤j≤N−1 denote thequantized version of the residual r_(i,j), where residual is differencebetween original block and the predicted block values. Then the blockDPCM is applied to the quantized residual samples, resulting in modifiedM×N array {tilde over (R)} with elements {tilde over (r)}_(i,j). Whenvertical Block Differential Pulse Code Modulation (BDPCM) is signalled:

$\begin{matrix}{{\overset{\sim}{r}}_{i,j} = \left\{ \begin{matrix}{{Q\left( r_{i,j} \right)},} & {{i = 0},{0 \leq j \leq \left( {N - 1} \right)}} \\{{{Q\left( r_{i,j} \right)} - {Q\left( r_{{({i - 1})},j} \right)}},} & {{1 \leq i \leq \left( {M - 1} \right)},{0 \leq j \leq \left( {N - 1} \right)}}\end{matrix} \right.} & \left( {2 - 7 - 1} \right)\end{matrix}$

For horizontal prediction, similar rules apply, and the residualquantized samples are obtained by

$\begin{matrix}{{\overset{\sim}{r}}_{i,j} = \left\{ \begin{matrix}{{Q\left( r_{i,j} \right)},} & {{0 \leq i \leq \left( {M - 1} \right)},{j = 0}} \\{{{Q\left( r_{i,j} \right)} - {Q\left( r_{i,{({j - 1})}} \right)}},} & {{0 \leq i \leq \left( {M - 1} \right)},{1 \leq j \leq \left( {N - 1} \right)}}\end{matrix} \right.} & \left( {2 - 7 - 2} \right)\end{matrix}$

The residual quantized samples i, are sent to the decoder.

On the decoder side, the above calculations are reversed to produceQ(r_(i,j)), 0≤i≤M−1, 0≤j≤N−1. For vertical prediction case,

Q(r _(i,j))=Σ_(k=0) ^(i) {tilde over (r)}_(k,j),0≤i≤(M−1),0≤j≤(N−1)  (2-7-3)

For horizontal case,

Q(r _(i,j))=Σ_(k=0) ^(j) {tilde over (r)}_(i,k),0≤i≤(M−1),0≤j≤(N−1)  (2-7-4)

The inverse quantized residuals, Q⁻¹ (Q(r_(i,j))), are added to theintra block prediction values to produce the reconstructed samplevalues.

The main benefit of this scheme is that the inverse DPCM can be done onthe fly during coefficient parsing simply adding the predictor as thecoefficients are parsed or it can be performed after parsing.

2.8 Adaptive Loop Filter

In the VTM5, an Adaptive Loop Filter (ALF) with block-based filteradaption is applied. For the luma component, one among 25 filters isselected for each 4×4 block, based on the direction and activity oflocal gradients.

2.8.1.1 Filter Shape

In the VTM5, two diamond filter shapes (as shown in FIG. 8 ) are used.The 7×7 diamond shape is applied for luma component and the 5×5 diamondshape is applied for chroma components.

FIG. 8 shows examples of ALF filter shapes (chroma: 5×5 diamond, luma:7×7 diamond)

2.8.1.2 Block Classification

For luma component, each 4×4 block is categorized into one out of 25classes. The classification index C is derived based on itsdirectionality D and a quantized value of activity Â, as follows:

C=5D+Â  (2-9-1)

To calculate D and Â, gradients of the horizontal, vertical and twodiagonal direction are first calculated using 1-D Laplacian:

g _(v)=Σ_(k=i−2) ^(i+3)Σ_(l=j−2) ^(j+3) V _(k,l) ,V_(k,l)=|2R(k,l)−R(k,l−1)−R(k,l+1)|  (2-9-2)

g _(h)=Σ_(k=i−2) ^(i+3)Σ_(l=j−2) ^(j+3) H _(k,l) ,H_(k,l)=|2R(k,l)−R(k−1,l)−R(k+1,l)|  (2-1)

g _(d1)=Σ_(k=i−2) ^(i+3)Σ_(l=j−3) ^(j+3) D1_(k,l),D1_(k,l)=|2R(k,l)−R(k−1,l−1)−R(k+1,l+1)|  (2-9-4)

g _(d2)=Σ_(k=i−2) ^(i+3)Σ_(j=j−2) ^(j+3) D2_(k,l),D2_(k,l)=|2R(k,l)−R(k−1,l+1)−R(k+1,l−1)|  (2-9-5)

Where indices i and j refer to the coordinates of the upper left samplewithin the 4×4 block and R(i,j) indicates a reconstructed sample atcoordinate (i,j).

To reduce the complexity of block classification, the subsampled 1-DLaplacian calculation is applied. As shown in FIG. 9 the same subsampledpositions are used for gradient calculation of all directions.

FIG. 9 shows an example of subsampled Laplacian calculation. (a)Subsampled positions for vertical gradient (b) Subsampled positions forhorizontal gradient (c) Subsampled positions for diagonal gradient (d)Subsampled positions for diagonal gradient.

Then D maximum and minimum values of the gradients of horizontal andvertical directions are set as:

g _(h,v) ^(max)=max(g _(h) ,g _(v) ,g _(h,v) ^(min)=min(g _(h) ,g_(v))  (2-9-6)

The maximum and minimum values of the gradient of two diagonaldirections are set as:

g _(d0,d1) ^(max)=max max(g _(d0) ,g _(d1)),g _(d0,d1) ^(min)=min(g_(d0) ,g _(d1))  (2-9-7)

To derive the value of the directionality D, these values are comparedagainst each other and with two thresholds t₁ and t₂:

Step 1. If both g_(h,v) ^(max)≤t₁·g_(h,v) ^(min) and g_(d0,d1)^(max)≤t₁·g_(h,v) ^(max) are true, D is set to 0.Step 2. If g_(h,v) ^(max)/g_(h,v) ^(min)>g_(d0,d1) ^(max)g_(d0,d1)^(min), continue from Step 3; otherwise continue from Step 4.Step 3. If g_(h,v) ^(max)>t₂·g_(h,v) ^(min), D is set to 2; otherwise Dis set to 1.Step 4. If g_(d0,d1) ^(max)t₂·g_(d0,d1) ^(min), D is set to 4; otherwiseD is set to 3.

The activity value A is calculated as:

A=Σ _(k=i−2) ^(i+3)Σ_(l=j−2) ^(j+3)(V _(k,l) +H _(k,l))  (2-9-8)

A is further quantized to the range of 0 to 4, inclusively, and thequantized value is denoted as Â.

For chroma components in a picture, no classification method is applied,i.e. a single set of ALF coefficients is applied for each chromacomponent.

2.8.1.3 Geometric Transformations of Filter Coefficients and ClippingValues

Before filtering each 4×4 luma block, geometric transformations such asrotation or diagonal and vertical flipping are applied to the filtercoefficients f(k, l) and to the corresponding filter clipping valuesc(k, l) depending on gradient values calculated for that block. This isequivalent to applying these transformations to the samples in thefilter support region. The idea is to make different blocks to which ALFis applied more similar by aligning their directionality.

Three geometric transformations, including diagonal, vertical flip androtation are introduced:

Diagonal: f _(D)(k,l)=f(l,k),c _(D)(k,l)=c(l,k),  (2-9-9)

Vertical flip: f _(V)(k,l)=f(k,K−l−1),c _(V)(k,l)=c(k,K−l−1)  (2-9-10)

Rotation: f _(R)(k,l)=f(K−l−1,k),c _(R)(k,l)=c(K−l−1,k)  (2-9-11)

where K is the size of the filter and 0≤k, l≤K−1 are coefficientscoordinates, such that location (0,0) is at the upper left corner andlocation (K−1, K−1) is at the lower right corner. The transformationsare applied to the filter coefficients f(k, l) and to the clippingvalues c(k, l) depending on gradient values calculated for that block.The relationship between the transformation and the four gradients ofthe four directions are summarized in the following table.

TABLE 2-5 Mapping of the gradient calculated for one block and thetransformations Gradient values Transformation g_(d2) < g_(d1) and g_(h)< g_(v) No transformation g_(d2) < g_(d1) and g_(v) < g_(h) Diagonalg_(d1) < g_(d2) and g_(h) < g_(v) Vertical flip g_(d1) < g_(d2) andg_(v) < g_(h) Rotation

2.8.1.4 Filter Parameters Signalling

In the VTM5, ALF filter parameters are signalled in Adaptation ParameterSet (APS). In one APS, up to 25 sets of luma filter coefficients andclipping value indexes, and up to one set of chroma filter coefficientsand clipping value indexes could be signalled. To reduce bits overhead,filter coefficients of different classification can be merged. In sliceheader, the indices of the APSs used for the current slice aresignalled.

Clipping value indexes, which are decoded from the APS, allowdetermining clipping values using a Luma table of clipping values and aChroma table of clipping values. These clipping values are dependent ofthe internal bitdepth. More precisely, the Luma table of clipping valuesand Chroma table of clipping values are obtained by the followingformulas:

$\begin{matrix}{{{AlfClip}_{L} = \left\{ {{{{round}\left( 2^{B\frac{N - n + 1}{N}} \right)}{for}n} \in \left\lbrack {1\ldots N} \right\rbrack} \right\}},} & \left( {2 - 9 - 12} \right)\end{matrix}$ $\begin{matrix}{{AlfClip}_{C} = \left\{ {{{{round}\left( 2^{{({B - 8})} + {8\frac{({N - n})}{N - 1}}} \right)}{for}n} \in \left\lbrack {1\ldots N} \right\rbrack} \right\}} & \left( {2 - 9 - 13} \right)\end{matrix}$

with B equal to the internal bitdepth and N equal to 4 which is thenumber of allowed clipping values in VTM5.0.

The filtering process can be controlled at coding tree block (CTB)level. A flag is always signalled to indicate whether ALF is applied toa luma CTB. A luma CTB can choose a filter set among 16 fixed filtersets and the filter sets from APSs. A filter set index is signaled for aluma CTB to indicate which filter set is applied. The 16 fixed filtersets are pre-defined and hard-coded in both the encoder and the decoder.

The filter coefficients are quantized with norm equal to 128. In orderto restrict the multiplication complexity, a bitstream conformance isapplied so that the coefficient value of the non-central position shallbe in the range of −2⁷ to 2⁷−1, inclusive. The central positioncoefficient is not signalled in the bitstream and is considered as equalto 128.

2.8.1.5 Filtering Process

At decoder side, when ALF is enabled for a CTB, each sample R(i,j)within the CU is filtered, resulting in sample value R′(i,j) as shownbelow,

R′(i,j)=R(i,j)+((Σ_(k≠0)Σ_(i≠0)f(k,l)×K(R(i+k,j+l)−R(i,j),c(k,l))+64)>>7)  (2-9-14)

where f(k, l) denotes the decoded filter coefficients, K(x,y) is theclipping function and c(k, l) denotes the decoded clipping parameters.The variable k and l varies between

$- \frac{L}{2}{and}\frac{L}{2}$

where L denotes the filter length. The clipping function K(x, y)=min(y,max(−y, x)) which corresponds to the function Clip3 (−y, y, x).

2.8.1.6 Virtual Boundary Filtering Process for Line Buffer Reduction

In VTM5, to reduce the line buffer requirement of ALF, modified blockclassification and filtering are employed for the samples nearhorizontal CTU boundaries. For this purpose, a virtual boundary isdefined as a line by shifting the horizontal CTU boundary with “N”samples as shown in FIG. 10 with N equal to 4 for the Luma component and2 for the Chroma component.

FIG. 10 shows an example of a modified block classification at virtualboundaries.

Modified block classification is applied for the Luma component asdepicted in FIG. 11 activity value A is accordingly scaled by takinginto account the reduced number of samples used in 1-D Laplaciangradient calculation.

For filtering processing, symmetric padding operation at the virtualboundaries are used for both Luma and Chroma components. As shown inFIG. 11 , when the sample being filtered is located below the virtualboundary, the neighboring samples that are located above the virtualboundary are padded. Meanwhile, the corresponding samples at the othersides are also padded, symmetrically.

FIG. 11 shows examples of modified ALF filtering for Luma component atvirtual boundaries.

2.9 Sample Adaptive Offset (SAO)

Sample adaptive offset (SAO) is applied to the reconstructed signalafter the deblocking filter by using offsets specified for each CTB bythe encoder. The HEVC test model (HM) encoder first makes the decisionon whether or not the SAO process is to be applied for current slice. IfSAO is applied for the slice, each CTB is classified as one of five SAOtypes as shown in Table 2-. The concept of SAO is to classify pixelsinto categories and reduces the distortion by adding an offset to pixelsof each category. SAO operation includes Edge Offset (EO) which usesedge properties for pixel classification in SAO type 1-4 and Band Offset(BO) which uses pixel intensity for pixel classification in SAO type 5.Each applicable CTB has SAO parameters including sao_merge_left_flag,sao_merge_up_flag, SAO type and four offsets. If sao_merge_left_flag isequal to 1, the current CTB will reuse the SAO type and offsets of theCTB to the left. If sao_merge_up_flag is equal to 1, the current CTBwill reuse SAO type and offsets of the CTB above.

TABLE 2-6 Specification of SAO type sample adaptive offset type toNumber of SAO type be used categories 0 None 0 1 1-D 0-degree patternedge offset 4 2 1-D 90-degree pattern edge offset 4 3 1-D 135-degreepattern edge 4 offset 4 1-D 45-degree pattern edge offset 4 5 bandoffset 4

2.9.1 Operation of Each SAO Type

Edge offset uses four 1-D 3-pixel patterns for classification ofthecurrent pixel p by consideration of edge directional information, asshown in FIG. 12 . From left to right these are: 0-degree, 90-degree,135-degree and 45-degree.

FIG. 12 shows examples of our 1-D 3-pixel patterns for the pixelclassification in E.

Each CTB is classified into one of five categories according to Table2-7.

TABLE 2-7 Pixel classification rule for EO Category Condition Meaning 0None of the below Largely monotonic 1 p < 2 neighbours Local minimum 2 p< 1 neighbour && p == 1 Edge neighbour 3 p > 1 neighbour && p == 1 Edgeneighbour 4 p > 2 neighbours Local maximum

Band offset (BO) classifies all pixels in one CTB region into 32 uniformbands by using the five most significant bits of the pixel value as theband index. In other words, the pixel intensity range is divided into 32equal segments from zero to the maximum intensity value (e.g., 255 for8-bit pixels). Four adjacent bands are grouped together and each groupis indicated by its most left-hand position as shown in FIG. 13 . Theencoder searches all position to get the group with the maximumdistortion reduction by compensating offset of each band.

FIG. 13 shows an example of four bands are grouped together andrepresented by its starting band position

2.10 Combined Inter and Intra Prediction (CIIP)

In VTM5, when a CU is coded in merge mode, if the CU contains at least64 luma samples (that is, CU width times CU height is equal to or largerthan 64), and if both CU width and CU height are less than 128 lumasamples, an additional flag is signalled to indicate if the combinedinter/intra prediction (CIIP) mode is applied to the current CU. As itsname indicates, the CIIP prediction combines an inter prediction signalwith an intra prediction signal. The inter prediction signal in the CIIPmode P_(inter) is derived using the same inter prediction processapplied to regular merge mode; and the intra prediction signal P_(intra)is derived following the regular intra prediction process with theplanar mode. Then, the intra and inter prediction signals are combinedusing weighted averaging, where the weight value is calculated dependingon the coding modes of the top and left neighbouring blocks (depicted inFIG. 14 ) as follows:

-   -   If the top neighbor is available and intra coded, then set        isIntraTop to 1, otherwise set isIntraTop to 0;    -   If the left neighbor is available and intra coded, then set        isIntraLeft to 1, otherwise set isIntraLeft to 0;    -   If (isIntraLeft+isIntraLeft) is equal to 2, then wt is set to 3;    -   Otherwise, if (isIntraLeft+isIntraLeft) is equal to 1, then wt        is set to 2;    -   Otherwise, set wt to 1.

The CIIP prediction is formed as follows:

P _(CHP)=((4−wt)*P _(inter) +wt*P _(intra)+2)>>2  (3-2)

FIG. 14 shows examples of Top and left neighboring blocks used in CIIPweight derivation

2.11 Luma Mapping with Chroma Scaling (LMCS)

In VTM5, a coding tool called the luma mapping with chroma scaling(LMCS) is added as a new processing block before the loop filters. LMCShas two main components: 1) in-loop mapping of the luma component basedon adaptive piecewise linear models; 2) for the chroma components,luma-dependent chroma residual scaling is applied. FIG. 15 shows theLMCS architecture from decoder's perspective. The dotted blocks in FIG.15 indicate where the processing is applied in the mapped domain; andthese include the inverse quantization, inverse transform, luma intraprediction and adding of the luma prediction together with the lumaresidual. The unpatterned blocks in FIG. 15 indicate where theprocessing is applied in the original (i.e., non-mapped) domain; andthese include loop filters such as deblocking, ALF, and SAO, motioncompensated prediction, chroma intra prediction, adding of the chromaprediction together with the chroma residual, and storage of decodedpictures as reference pictures. The checkered blocks in FIG. 15 are thenew LMCS functional blocks, including forward and inverse mapping of theluma signal and a luma-dependent chroma scaling process. Like most othertools in VVC, LMCS can be enabled/disabled at the sequence level usingan SPS flag.

FIG. 15 shows examples of Luma mapping with chroma scaling architecture.

2.12 Dualtree Partitioning

In the current VVC design, for I slices, each CTU can be split intocoding units with 64×64 luma samples using an implicit quadtree splitand that these coding units are the root of two separate coding_treesyntax structure for luma and chroma.

Since the dual tree in intra picture allows to apply differentpartitioning in the chroma coding tree compared to the luma coding tree,the dual tree introduces longer coding pipeline and the QTBT MinQTSizeCvalue range and MinBtSizeY and MinTTSizeY in chroma tree allow smallchroma blocks such as 2×2, 4×2, and 2×4. It provides difficulties inpractical decoder design. Moreover, several prediction modes such asCCLM, planar and angular mode needs multiplication. In order toalleviate the above-mentioned issues, small chroma block sizes(2×2/2×4/4×2) are restricted in dual tree as a partitioning restriction.

2.13 Smallest Chroma Intra Prediction Unit (SCIPU) in JVET-00050

Small chroma size is not friendly to hardware implementation. Indualtree cases, chroma blocks with too small sizes are disallowed.However, in singletree cases, VVC draft 5 still allows 2×2, 2×4, 4×2chroma blocks. To restrict the size of chroma block, in single codingtree, a SCIPU is defined in JVET-00050 as a coding tree node whosechroma block size is larger than or equal to TH chroma samples and hasat least one child luma block smaller than 4TH luma samples, where TH isset to 16 in this contribution. It is required that in each SCIPU, allcoding blocks (CBs) are inter, or all CBs are non-inter, i.e., eitherintra or IBC. In case of a non-inter SCIPU, it is further required thatchroma of the non-inter SCIPU shall not be further split and luma of theSCIPU is allowed to be further split. In this way, the smallest chromaintra CB size is 16 chroma samples, and 2×2, 2×4, and 4×2 chroma CBs areremoved. In addition, chroma scaling is not applied in case of anon-inter SCIPU.

Two SCIPU examples are shown in FIG. 16 . In FIG. 16(a), one chroma CBof 8×4 chroma samples and three luma CBs (4×8, 8×8, 4×8 luma CBs) formone SCIPU because the ternary tree (TT) split from the 8×4 chromasamples would result in chroma CBs smaller than 16 chroma samples. InFIG. 16(b), one chroma CB of 4×4 chroma samples (the left side of the8×4 chroma samples) and three luma CBs (8×4, 4×4, 4×4 luma CBs) form oneSCIPU, and the other one chroma CB of 4×4 samples (the right side of the8×4 chroma samples) and two luma CBs (8×4, 8×4 luma CBs) form one SCIPUbecause the binary tree (BT) split from the 4×4 chroma samples wouldresult in chroma CBs smaller than 16 chroma samples.

FIG. 16 shows SCIPU examples.

The type of a SCIPU is inferred to be non-inter if the current slice isan I-slice or the current SCIPU has a 4×4 luma partition in it afterfurther split one time (because no inter 4×4 is allowed in VVC);otherwise, the type of the SCIPU (inter or non-inter) is indicated byone signalled flag before parsing the CUs in the SCIPU.

2.14 Small Chroma Block Constrains in VVC Draft 6

In VVC draft 6 (JVET-02001-vE.docx), the constrains on small chromablocks are implemented as follows (related part is marked in

).

coding_tree( x0, y0, cbWidth, cbHeight, qgOnY, qgOnC, cbSubdiv,cqtDepth, mttDepth, depthOffset, partIdx,

 

 ) { Descriptor  . . .  if( split_cu_flag ) {   if( ( allowSplitBtVer || allowSplitBtHor | | allowSplitTtVer | | allowSplitTtHor ) &&         allowSplitQT )     split_qt_flag ae(v)   if( !split_qt_flag ) {    if(  (  allowSplitBtHor    | |    allowSplitTtHor  )  &&          (allowSplitBtVer | | allowSplitTtVer ) )         mtt_split_cu_vertical_flag ae(v)    if(  (  allowSplitBtVer    &&    allowSplitTtVer    &&mtt_split_cu_vertical_flag         )               | |         (  allowSplitBtHor     &&     allowSplitTtHor &&!mtt_split_cu_vertical_flag ) )          mtt_split_cu_binary_flag ae(v)  }   

    

  

    

ae(v)   

   

    

   

   

   if( !split_qt_flag ) {     if( MttSplitMode[ x0 ] [ y0 ] [ mttDepth ]= = SPLIT_BT_VER ) {  depthOffset += ( x0 + cbWidth >pic_width_in_luma_samples ) ? 1 : 0          x1 = x0 + ( cbWidth / 2 )         coding_tree( x0, y0, cbWidth / 2, cbHeight, qgOnY, qgOnC,cbSubdiv + 1,  cqtDepth, mttDepth + 1, depthOffset, 0, treeType,modeType )          if( x1 < pic_width_in_luma_samples )  coding_tree(x1, y0, cbWidth / 2, cbHeightY, qgOnY, qgOnC,    cbSubdiv + 1, cqtDepth, mttDepth + 1, depthOffset, 1, treeType, modeType )     } elseif( MttSplitMode[ x0 ] [ y0 ] [ mttDepth ] = = SPLIT_BT_HOR ) { depthOffset += ( y0 + cbHeight > pic_height_in_luma_samples ) ? 1 : 0         y1 = y0 + ( cbHeight / 2 )          coding_tree( x0, y0,cbWidth, cbHeight / 2, qgOnY, qgOnC, cbSubdiv + 1,  cqtDepth, mttDepth +1, depthOffset, 0, treeType, modeType )          if( y1 <pic_height_in_luma_samples )  coding_tree( x0, y1, cbWidth, cbHeight /2, qgOnY, qgOnC,     cbSubdiv + 1,  cqtDepth, mttDepth + 1, depthOffset,1, treeType, modeType )     } else if( MttSplitMode[ x0 ] [ y0 ] [mttDepth ] = = SPLIT_TT_VER ) {          x1 = x0 + (cbWidth / 4 )         x2 = x0 + ( 3 * cbWidth / 4 )          qgOnY = qgOnY && (cbSubdiv + 2 <= cu_qp_delta_subdiv )         qgOnC = qgOnC &&  (  cbSubdiv + 2    <=cu_chroma_qp_offset_subdiv )          coding_tree( x0, y0, cbWidth / 4,cbHeight, qgOnY, qgOnC, cbSubdiv + 2,  cqtDepth, mttDepth + 1,depthOffset, 0, treeType, modeType )          coding_tree( x1, y0,cbWidth / 2, cbHeight, qgOnY, qgOnC, cbSubdiv + 1,  cqtDepth, mttDepth +1, depthOffset, 1, treeType, modeType )          coding_tree( x2, y0,cbWidth / 4, cbHeight, qgOnY, qgOnC, cbSubdiv + 2,  cqtDepth, mttDepth +1, depthOffset, 2, treeType, modeType )         } else { /* SPLIT_TT_HOR*/          y1 = y0 + ( cbHeight / 4 )          y2 = y0 + ( 3 * cbHeight/ 4 )          qgOnY = qgOnY && ( cbSubdiv + 2 <= cu_qp_delta_subdiv )         qgOnC  =  qgOnC  &&  (  cbSubdiv + 2  <=cu_chroma_qp_offset_subdiv )          coding_tree( x0, y0, cbWidth,cbHeight / 4, qgOnY, qgOnC, cbSubdiv + 2,  cqtDepth, mttDepth + 1,depthOffset, 0, treeType, modeType )          coding_tree( x0, y1,cbWidth, cbHeight / 2, qgOnY, qgOnC, cbSubdiv + 1,  cqtDepth, mttDepth +1, depthOffset, 1, treeType, modeType ) coding_tree( x0, y2, cbWidth,cbHeight / 4, qgOnY, qgOnC, cbSubdiv + 2,  cqtDepth, mttDepth + 1,depthOffset, 2, treeType, modeType )    }   } else {    x1 = x0 + (cbWidth / 2 )    y1 = y0 + ( cbHeight / 2 )    coding_tree( x0, y0,cbWidth / 2, cbHeight / 2, qgOnY, qgOnC, cbSubdiv + 2,  cqtDepth + 1, 0,0, 0, treeType, modeType )    if( x1 < pic_width_in_luma_samples )         coding_tree( x1, y0, cbWidth / 2, cbHeight / 2, qgOnY, qgOnC,cbSubdiv + 2,  cqtDepth + 1, 0, 0, 1, treeType, modeType )    if( y1 <pic_height_in_luma_samples )          coding_tree( x0, y1, cbWidth / 2,cbHeight / 2, qgOnY, qgOnC, cbSubdiv + 2,  cqtDepth + 1, 0, 0, 2,treeType, modeType )   if(  y1  <  pic_height_in_luma_samples    &&    x1  <pic_width_in_luma_samples )          coding_tree( x1, y1, cbWidth / 2,cbHeight / 2, qgOnY, qgOnC, cbSubdiv + 2,  cqtDepth + 1, 0, 0, 3,treeType, modeType )   }   

 

 

         

 

         

         

           

 

  

 } else   coding_unit( x0, y0, cbWidth, cbHeight, cqtDepth,treeTypeCurr, modeTypeCurr ) }

2.14.1.1 Coding Unit Syntax

coding_unit( x0, y0, cbWidth, cbHeight, cqtDepth, treeType, modeType ) {Descriptor  chType = treeType = = DUAL_TREE_CHROMA? 1 : 0  if(slice_type != I | | sps_ibc_enabled_flag | | sps_palette_enabled_flag) {  if(   treeType   !=   DUAL_TREE_CHROMA     &&    !( ( ( cbWidth = = 4&& cbHeight = = 4 ) | | modeType = = MODE_TYPE_INTRA    &&!sps_ibc_enabled_flag ) )    cu_skip_flag[ x0 ] [ y0 ] ae(v)  if( cu_skip_flag[ x0 ][ y0 ] = = 0  &&   slice_type   !=   I    && !(cbWidth = = 4 && cbHeight = = 4 ) && modeType = = MODE_TYPE_ALL )   pred_mode_flag ae(v)   if( ( ( slice_type = = I  &&   cu_skip_flag[x0 ] [ y0 ] = =0 )   | |    ( slice_type != I  &&  ( CuPredMode[ chType][ x0 ][ y0 ]  != MODE_INTRA     ( cbWidth = = 4 && cbHeight = = 4 &&cu_skip_flag[ x0 ] [ y0 ] = = 0 ) ) ) )                              &&   cbWidth <= 64  &&  cbHeight <= 64  &&  modeType !=MODE_TYPE_INTER                       &&    sps_ibc_enabled_flag &&treeType != DUAL_TREE_CHROMA )    pred_mode_ibc_flag ae(v)   if( ( ( (slice_type = = I | | ( cbWidth = = 4 && cbHeight = = 4 ) | |sps_ibc_enabled_flag        )               &&      CuPredMode[ x0 ] [y0 ]   = =   MODE_INTRA )    | |     ( slice_type != I && !( cbWidth = =4 && cbHeight = = 4 ) && !sps_ibc_enabled_flag     &&   CuPredMode[ x0][ y0 ] != MODE_INTRA ) )   &&sps_palette_enabled_flag                      &&     cbWidth <= 64 &&cbHeight <= 64 && && cu_skip_flag[ x0 ] [ y0 ] ==         0                     &&     modeType != MODE_INTER )   pred_mode_plt_flag ae(v)  } . . .

-   -   -   

        -   

    -   ,        -   

        -   

        -   

        -   

    -   -   

        -   

    -   

Allowed quad split process

Inputs to this process are:

-   -   a coding block size cbSize in luma samples,    -   a multi-type tree depth mttDepth,    -   a variable treeType specifying whether a single tree        (SINGLE_TREE) or a dual tree is used to partition the CTUs and,        when a dual tree is used, whether the luma (DUAL_TREE_LUMA)    -   ,        .        .

Output of this process is the variable allowSplitQt.

The variable allowSplitQt is derived as follows:

-   -   If one or more of the following conditions are true,        allowSplitQt is set equal to FALSE:        -   treeType is equal to SINGLE_TREE or DUAL_TREE_LUMA and            cbSize is less than or equal to MinQtSizeY

        -   treeType is equal to DUAL_TREE_CHROMA and cbSize/SubWidthC            is less than or equal to MinQtSizeC

        -   mttDepth is not equal to 0

        -   treeType is equal to DUAL_TREE_CHROMA and (cbSize/SubWidthC)            is less than or equal to 4

        -       -   Otherwise, allowSplitQt is set equal to TRUE.

Allowed binary split process

Inputs to this process are:

-   -   a binary split mode btSplit,    -   a coding block width cbWidth in luma samples,    -   a coding block height cbHeight in luma samples,    -   a location (x0, y0) of the top-left luma sample of the        considered coding block relative to the top-left luma sample of        the picture,    -   a multi-type tree depth mttDepth,    -   a maximum multi-type tree depth with offset maxMttDepth,    -   a maximum binary tree size maxBtSize,    -   a minimium quadtree size minQtSize,    -   a partition index partIdx,    -   a variable treeType specifying whether a single tree        (SINGLE_TREE) or a dual tree is used to partition the CTUs and,        when a dual tree is used, whether the luma (DUAL_TREE_LUMA) or        chroma components (DUAL_TREE_CHROMA) are currently processed,    -   ,        ,        ,        ,        ,        ,        ,        .

Output of this process is the variable allowBtSplit.

TABLE 6-2 Specification of parallelTtSplit and cbSize based on btSplit.btSplit = = btSplit = = SPLIT_BT_VER SPLIT_BT_HOR parallelTtSplitSPLIT_TT_VER SPLIT_TT_HOR cbSize cbWidth cbHeight

The variables parallelTtSplit and cbSize are derived as specified inTable 6-2.

The variable allowBtSplit is derived as follows:

-   -   If one or more of the following conditions are true,        allowBtSplit is set equal to FALSE:        -   cbSize is less than or equal to MinBtSizeY

        -   cbWidth is greater than maxBtSize

        -   cbHeight is greater than maxBtSize

        -   mttDepth is greater than or equal to maxMttDepth

        -   treeType is equal to DUAL_TREE_CHROMA and            (cbWidth/SubWidthC)*(cbHeight/SubHeightC) is less than or            equal to 16

        -       -   Otherwise, if all of the following conditions are true,        allowBtSplit is set equal to FALSE        -   btSplit is equal to SPLIT_BT_VER        -   y0+cbHeight is greater than pic_height_in_luma_samples    -   Otherwise, if all of the following conditions are true,        allowBtSplit is set equal to FALSE        -   btSplit is equal to SPLIT_BT_VER        -   cbHeight is greater than MaxTbSizeY        -   x0+cbWidth is greater than pic_width_in_luma_samples    -   Otherwise, if all of the following conditions are true,        allowBtSplit is set equal to FALSE        -   btSplit is equal to SPLIT_BT_HOR        -   cbWidth is greater than MaxTbSizeY        -   y0+cbHeight is greater than pic_height_in_luma_samples    -   Otherwise, if all of the following conditions are true,        allowBtSplit is set equal to FALSE        -   x0+cbWidth is greater than pic_width_in_luma_samples        -   y0+cbHeight is greater than pic_height_in_luma_samples        -   cbWidth is greater than minQtSize    -   Otherwise, if all of the following conditions are true,        allowBtSplit is set equal to FALSE        -   btSplit is equal to SPLIT_BT_HOR        -   x0+cbWidth is greater than pic_width_in_luma_samples        -   y0+cbHeight is less than or equal to            pic_height_in_luma_samples    -   Otherwise, if all of the following conditions are true,        allowBtSplit is set equal to FALSE:        -   mttDepth is greater than 0        -   partIdx is equal to 1        -   MttSplitMode[x0][y0][mttDepth−1] is equal to parallelTtSplit    -   Otherwise, if all of the following conditions are true,        allowBtSplit is set equal to FALSE        -   btSplit is equal to SPLIT_BT_VER        -   cbWidth is less than or equal to MaxTbSizeY        -   cbHeight is greater than MaxTbSizeY    -   Otherwise, if all of the following conditions are true,        allowBtSplit is set equal to FALSE        -   btSplit is equal to SPLIT_BT_HOR        -   cbWidth is greater than MaxTbSizeY        -   cbHeight is less than or equal to MaxTbSizeY    -   Otherwise, allowBtSplit is set equal to TRUE.

Allowed ternary split process

Inputs to this process are:

-   -   a ternary split mode ttSplit,    -   a coding block width cbWidth in luma samples,    -   a coding block height cbHeight in luma samples,    -   a location (x0, y0) of the top-left luma sample of the        considered coding block relative to the top-left luma sample of        the picture,    -   a multi-type tree depth mttDepth    -   a maximum multi-type tree depth with offset maxMttDepth,    -   a maximum ternary tree size maxTtSize,    -   a variable treeType specifying whether a single tree        (SINGLE_TREE) or a dual tree is used to partition the CTUs and,        when a dual tree is used, whether the luma (DUAL_TREE_LUMA) or        chroma components (DUAL_TREE_CHROMA) are currently processed,    -   ,        ,        ,        ,

Output of this process is the variable allowTtSplit.

TABLE 6-3 Specification of cbSize based on ttSplit. ttSplit = = ttSplit= = SPLIT_TT_VER SPLIT_TT_HOR cbSize cbWidth cbHeight

The variable cbSize is derived as specified in Table 6-3.

The variable allowTtSplit is derived as follows:

-   -   If one or more of the following conditions are true,        allowTtSplit is set equal to FALSE:        -   cbSize is less than or equal to 2*MinTtSizeY

        -   cbWidth is greater than Min(MaxTbSizeY, maxTtSize)

        -   cbHeight is greater than Min(MaxTbSizeY, maxTtSize)

        -   mttDepth is greater than or equal to maxMttDepth

        -   x0+cbWidth is greater than pic_width_in_luma_samples

        -   y0+cbHeight is greater than pic_height_in_luma_samples

        -   treeType is equal to DUAL_TREE_CHROMA and            (cbWidth/SubWidthC)*(cbHeight/SubHeightC) is less than or            equal to 32

        -       -   Otherwise, allowTtSplit is set equal to TRUE.

pred_mode_flag equal to 0 specifies that the current coding unit iscoded in inter prediction mode.

pred_mode_flag equal to 1 specifies that the current coding unit iscoded in intra prediction mode.

When pred_mode_flag is not present, it is inferred as follows:

-   -   If cbWidth is equal to 4 and cbHeight is equal to 4,        pred_mode_flag is inferred to be equal to 1.    -   ,        .    -   ,        ,    -   Otherwise, pred_mode_flag is inferred to be equal to 1 when        decoding an I slice, and equal to 0 when decoding a P or B        slice, respectively.

The variable CuPredMode[chType][x][y] is derived as follows for x=x0 . .. x0+cbWidth−1 and y=y0 . . . y0+cbHeight−1:

-   -   If pred_mode_flag is equal to 0, CuPredMode[chType][x][y] is set        equal to MODE_INTER.    -   Otherwise (pred_mode_flag is equal to 1),        CuPredMode[chType][x][y] is set equal to MODE_INTRA.

pred_mode_ibc_flag equal to 1 specifies that the current coding unit iscoded in IBC prediction mode. pred_mode_ibc_flag equal to 0 specifiesthat the current coding unit is not coded in IBC prediction mode.

When pred_mode_ibc_flag is not present, it is inferred as follows:

-   -   If cu_skip_flag[x0][y0] is equal to 1, and cbWidth is equal to        4, and cbHeight is equal to 4, pred_mode_ibc_flag is inferred to        be equal 1.    -   Otherwise, if both cbWidth and cbHeight are equal to 128,        pred_mode_ibc_flag is inferred to be equal to 0.    -   ,        ,        .    -   ,        ,        .    -   Otherwise, pred_mode_ibc_flag is infered to be equal to the        value of sps_ibc_enabled_flag when decoding an I slice, and 0        when decoding a P or B slice, respectively.

When pred_mode_ibc_flag is equal to 1, the variableCuPredMode[chType][x][y] is set to be equal to MODE_IBC for x=x0 . . .x0+cbWidth−1 and y=y0 . . . y0+cbHeight−1.

3. PROBLEMS

-   1. Currently IBC is considered as MODE_TYPE_INTRA and thus small    chroma block is disallowed, which leads to unnecessary coding    efficiency loss.-   2. Currently palette is considered as MODE_TYPE_INTRA and thus small    chroma block is disallowed, which leads to unnecessary coding    efficiency loss.-   3. Currently small chroma block constrains do not consider color    subsampling format.-   4. Currently same partition and prediction mode constraints on small    blocks is applied to all chroma formats. However, it may be    desirable to design different constraint mechanisms on small blocks    in 4:2:0 and 4:2:2 chroma formats.-   5. Currently the Palette mode flag signaling depends on the    modeType, which is not desirable as palette may be not apply small    block constraints.-   6. Currently the IBC mode flag is inferred to be 0 for P/B slice    with cu_skip_flag equal to 1 but MODE_TYPE equal to MODE_TYPE_INTRA,    this is illegal in the syntax parsing.-   7. Currently, non-4×4 luma IBC mode is not allowed for SCIPU luma    blocks, which may be not desirable and may cause coding efficiency    loss.-   8. 2×H chroma block is still allowed, which is not friendly to    hardware implementation.-   9. CIIP is considered as of MODE_INTER while it uses intra    prediction, which breaks the constrains in some cases.-   10. When SCIPU is applied, delta quantization parameter (QP) for    chroma may be signaled depending on the luma splitting. For example,    when the current block dimensions are 16×8 in luma samples and are    split with vertical TT, a local dual tree may be applied. It is    specified that    -   qgOnC=qgOnC && (cbSubdiv+2<=cu_chroma_qp_offset_subdiv)    -   So qgOnC is set to zero if        cbSubdiv+2<=cu_chroma_qp_offset_subdiv. This conditional setting        assumes that the chroma component is also split by TT. With the        local dual tree, the chroma component may not be split, thus        cbSubdiv may be larger than cu_chroma_qp_offset_subdiv.        IsCuChromaQpOffsetCoded should be set to be 0 to allow signaling        delta QP for chroma. However, IsCuChromaQpOffsetCoded is not set        to be 0 because qgOnC is set to be 0.-   11. The maximum transform size for lossless coding may be set    differently from the maximum transform size for lossy coding.

4. EXAMPLES OF TECHNICAL SOLUTIONS AND EMBODIMENTS

The listing below should be considered as examples. These techniquesshould not be interpreted in a narrow way. Furthermore, these techniquescan be combined in any manner.

In this disclosure, “M×N coding tree node” indicates a M×N block, with Mas the block width and N as the block height in luma samples, which maybe further partitioned, such as by quadtree (QT)/binary tree(BT)/ternary tree (TT). For example, a block could be a QT node, or a BTnode, or a TT node. A coding tree node could be a coding unit (e.g.,with three color components for single tree, with two chroma colorcomponents for dual tree chroma coding, and only luma color componentfor dual tree luma coding), or a luma coding block, or a chroma codingblock. A “small coding tree node unit” may indicate a coding tree nodewith block size M×N equal to 32/64/128 in luma samples.

If not specifically mentioned, the width W and height H for a codingblock is measured in luma samples. For example, M×N coding block means aM×N luma block, and/or two (M/SubWidthC)×(N/SubHeightC) chroma blocks,where SubWidthC and SubHeightC are derived by chroma format as below.

chroma_format_ separate_colour_ Chroma Sub- Sub- idc plane_flag formatWidthC HeightC 0 0 Mono- 1 1 chrome 1 0 4:2:0 2 2 2 0 4:2:2 2 1 3 04:4:4 1 1 3 1 4:4:4 1 1

-   1. Whether and/or how to partition into small blocks may depend on    color formats.    -   a. In one example, for 4:4:4 color format, the constrains on the        sizes of chroma blocks may follow those constrains on luma        blocks.    -   b. In one example, for 4:2:2 color format, the constrains on the        sizes of chroma blocks may follow those constrains for 4:2:0        color format.    -   c. In one example, for 4:0:0, and/or 4:4:4 chroma format, the        constraints on small block partitions and/or prediction modes        may be not applied.    -   d. In one example, the constraints on small block partitions        and/or prediction modes may be applied differently for different        chroma formats.        -   i. In one example, for M×N (such as 8×8) coding tree node            with horizontal BT split, in 4:2:2 chroma format, the            horizontal BT split may be allowed for both chroma block and            luma block, while in 4:2:0 chroma format, the horizontal BT            split may be allowed for luma block but disabled for chroma            block.        -   ii. In one example, for M×N (such as 16×4) coding tree node            with vertical BT split, in 4:2:2 chroma format, the vertical            BT split may be allowed for both chroma block and luma            block, while in 4:2:0 chroma format, the vertical BT split            may be allowed for luma block but disabled for chroma block.        -   iii. In one example, for M×N (such as 8×16) coding tree node            with horizontal TT split, in 4:2:2 chroma format, the            horizontal TT split may be allowed for both chroma block and            luma block, while in 4:2:0 chroma format, the horizontal TT            split may be allowed for luma block but disabled for chroma            block.        -   iv. In one example, for M×N (such as 32×4) coding tree node            with vertical TT split, in 4:2:2 chroma format, the vertical            TT split may be allowed for both chroma block and luma            block, while in 4:2:0 chroma format, the vertical TT split            may be allowed for luma block but disabled for chroma block.        -   v. In one example, for 4:0:0, and/or 4:4:4 color formats,            small block constraints may be not applied.    -   e. In one example, whether to enable SCIPU is dependent on the        color format.        -   i. In one example, SCIPU is enabled for 4:2:0 and 4:2:2            color formats.        -   ii. In one example, SCIPU is disabled for 4:0:0 and/or 4:4:4            color format.            -   1. In one example, modeType may be always equal to                MODE_TYPE_ALL for 4:0:0 and/or 4:4:4 color format.        -   2. In one example, modeTypeCondition may be always equal to            0 for 4:0:0 and/or 4:4:4 color format.-   2. How to determine the prediction modes (and/or modeType) for    (sub-)blocks of a coding tree node may depend on chroma formats.    -   a. In one example, if one of the below conditions is true, the        modeType of (sub-)blocks partitioned by this coding tree node        may be equal to MODE_TYPE_ALL for 4:2:2 chroma format, while for        4:2:0 chroma format, the modeType may be equal to either        MODE_TYPE_INTRA or MODE_TYPE_INTER.        -   i. M×N (such as 8×8) coding tree node with horizontal BT            split        -   ii. M×N (such as 16×4) coding tree node with vertical BT            split        -   iii. M×N (such as 8×16) coding tree node with horizontal TT            split        -   iv. M×N (such as 32×4) coding tree node with vertical TT            split-   3. It is proposed to rename MODE_TYPE_INTRA to MODE_TYPE_NO_INTER    and restrict the usage of MODE_INTER.    -   a. In one example, when modeType of a coding unit is equal to        MODE_TYPE_NO_INTER, MODE_INTER may be disallowed.-   4. It is proposed to rename MODE_TYPE_INTER to MODE_TYPE_NO_INTRA    and restrict the usage of MODE_INTRA.    -   a. In one example, when modeType of a coding unit is equal to        MODE_TYPE_NO_INTRA, MODE_INTRA may be disallowed.-   5. The mode constraint flag may be never signaled in 4:2:2 and/or    4:0:0 and/or 4:4:4 chroma formats.    -   a. In one example, when mode constraint flag is not present, it        may be inferred to equal to be 1.        -   i. Alternatively, when mode constraint flag is not present,            it may be inferred to equal to be 0.-   6. Whether and/or how to apply SCIPU on an M×N coding block with M    as the block width and N as the block height may depend on whether    the color format is 4:2:0 or 4:2:2.    -   a. In one example, in 4:2:2 color format, for an M×N coding        block with M as the block width and N as the block height, SCIPU        may be enabled only if M multiplied by N (denoted by M*N) is        equal to 64 or 32.    -   b. In one example, a coding tree node with M*N=128 may be never        treated as SCIPU block in 4:2:2 color format.    -   c. In one example, a coding tree node with BT split and M*N=64        may be never treated as SCIPU block in 4:2:2 color format.    -   d. In one example, a coding tree node with split_qt_flag equal        to 1 and M*N=64, may be an SCIPU block in 4:2:2 color format.    -   e. In one example, a coding tree node with TT split and M*N=64,        may be treated as SCIPU block in 4:2:2 color format.    -   f. In one example, a coding tree node with BT split and M*N=32,        may be treated as SCIPU block in 4:2:2 color format.    -   g. In above description, for an SCIPU block in 4:2:2 color        format, the modeTypeCondition may be always equal to 1.    -   h. In above description, for an SCIPU block in 4:2:2 color        format, only MODE_TYPE_INTRA may be allowed for both the current        block in parent node and all sub-blocks under child leaf nodes.-   7. In 4:2:2 color format, modeTypeCondition of an SCIPU block may be    always equal to 1.    -   a. In one example, modeTypeCondition may be equal to 0 or 1 for        4:2:2 color format.    -   b. In one example, for SCIPU blocks in 4:2:2 color format,        modeTypeCondition may be never equal to 2.-   8. In 4:2:2 color format, modeType of an SCIPU block may be always    equal to MODE_TYPE_INTRA.    -   a. In one example, modeType may be equal to MODE_TYPE_ALL or        MODE_TYPE_INTRA in 4:2:2 color format.    -   b. In one example, for SCIPU blocks in 4:2:2 color format,        MODE_TYPE_INTER may be disabled.-   9. Whether the block partition is allowed or not may be dependent on    the modeType, and/or the block size.    -   a. In one example, whether BT and/or TT split is allowed for a        block may be dependent on the modeType.        -   i. In one example, if modeType is equal to MODE_TYPE_INTER,            then BT split may be disallowed for the current coding block            (e.g., allowBtSplit is set equal to false).        -   ii. In one example, if modeType is equal to MODE_TYPE_INTER,            then TT split may be disallowed for the current coding block            (e.g., allowTtSplit is set equal to false).    -   b. In one example, whether BT and/or TT split is allowed for a        block may be dependent on the modeType and the block size.        -   i. In one example, for an M×N coding block, with M as the            block width and N as the block height, when M*N is less than            or equal to 32 and modeType is equal to MODE_TYPE_INTER, the            BT split may be disallowed (e.g., allowBtSplit is set equal            to false).        -   ii. In one example, for an M×N coding block, with M as the            block width and N as the block height, when M*N is less than            or equal to 64 and modeType is equal to MODE_TYPE_INTER, the            TT split may be disallowed (e.g., allowTtSplit is set equal            to false).-   10. When modeTypeCurr of a coding tree is equal to MODE_TYPE_INTER,    split of the coding tree may be restricted    -   a. In one example, when modeTypeCurr of a coding tree is equal        to MODE_TYPE_INTER, BT split may be disallowed.    -   b. In one example, when modeTypeCurr of a coding tree is equal        to MODE_TYPE_INTER, TT split may be disallowed.    -   c. In one example, when modeTypeCurr of a coding tree is equal        to MODE_TYPE_INTER, QT split may be disallowed.    -   d. In one example, when modeTypeCurr of a coding tree is equal        to MODE_TYPE_INTER and luma block size is less than or equal to        32, BT split may be disallowed.    -   e. In one example, when modeTypeCurr of a coding tree is equal        to MODE_TYPE_INTER and luma block size is less than or equal to        64, TT split may be disallowed.-   11. A coding unit with treeType being DUAL_TREE_LUMA may be coded in    inter mode.    -   a. In one example, coding unit coded in inter coding mode, i.e.        MODE_INTER may only contain luma component even for color        formats with multiple color components.    -   b. In one example, pred_mode_flag may need to be parsed for        DUAL_TREE_LUMA block.    -   c. In one example, for DUAL_TREE_LUMA block coded in inter mode,        the same constrains of inter mode for SINGLE_TREE may be also        applied.        -   i. In one example, 4×4 DUAL_TREE_LUMA inter block may be            disallowed.-   12. Chroma intra (and/or IBC) blocks with block width equal to M    (such as M=2) chroma samples may be not allowed.    -   a. In one example, 2×N (such as N<=64) chroma intra blocks may        be not allowed in dual tree.        -   i. In one example, when treeType is equal to            DUAL_TREE_CHROMA and the block width is equal to 4 chroma            samples, vertical BT split may be disabled.        -   ii. In one example, when treeType is equal to            DUAL_TREE_CHROMA and the block width is equal to 8 chroma            samples, vertical TT split may be disabled.    -   b. In one example, 2×N (such as N<=64) chroma intra (and/or IBC)        blocks may be not allowed in single tree.        -   i. In one example, for M×N (such as M=8 and N<=64) coding            tree node with vertical BT split, one of below process may            be applied.            -   1. Vertical BT split may be disallowed for the 4×N or                4×(N/2) chroma block but allowed for the 8×N luma block.            -   2. The 4×N or 4×(N/2) chroma block may be not vertical                BT split, and it may be coded by MODE_INTRA, or                MODE_IBC.            -   3. Vertical BT split may be allowed for both the 8×N                luma block and the 4×N or 4×(N/2) chroma block, but both                luma and chroma blocks not coded by MODE_INTRA (e.g.,                may be coded by MODE_INTER, or MODE_IBC).        -   ii. In one example, for M×N (such as M=16 and N<=64) coding            tree node with vertical TT split, one of below process may            be applied.            -   1. Vertical TT split may be disallowed for the 8×N or                8×(N/2) chroma block but allowed for the 16×N luma                block.            -   2. The 8×N or 8×(N/2) chroma block may be not vertical                TT split and coded by MODE_INTRA, or MODE_IBC.            -   3. Vertical TT split may be allowed for both the 16×N                luma block and the 8×N or 8×(N/2) chroma block, but both                luma and chroma blocks may be not coded by MODE_INTRA                (e.g., may be coded by MODE_INTER, or MODE_IBC).-   13. IBC mode may be allowed for luma and/or chroma blocks regardless    of whether it is of small block size.    -   a. In one example, IBC mode may be allowed for luma blocks        including 8×4/8×8/16×4 and 4×N (such as N<=64) luma blocks, even        if modeType is equal to MODE_TYPE_INTRA.    -   b. In one example, IBC mode may be allowed for chroma blocks,        even if modeType is equal to MODE_TYPE_INTRA.-   14. The signaling of IBC prediction mode flag may depend on    prediction mode type (e.g., MODE_TYPE_INTRA).    -   a. In one example, IBC prediction mode flag for a non-SKIP block        (e.g. a coding block which is not coded by skip mode) may be        explicitly signaled in the bitstream when the treeType is not        equal to DUAL_TREE_CHROMA and the modeType is equal to        MODE_TYPE_INTRA.-   15. IBC prediction mode flag may be inferred depending on the CU    SKIP flag and the mode type (e.g., modeType).    -   a. In one example, if the current block is coded with SKIP mode        (such as cu_skip_flag is equal to 1), and the modeType is equal        to MODE_TYPE_INTRA, the IBC prediction mode flag (such as        pred_mode_ibc_flag) may be inferred to be equal to 1.-   16. The explicit signaling of Palette mode flag may not depend on    the modeType.    -   a. In one example, palette mode flag (such as        pred_mode_plt_flag) signaling may depend on the slice type,        block size, prediction mode, etc., But no matter what the        modeType is.    -   b. In one example, palette mode flag (such as        pred_mode_plt_flag) is inferred to be 0 when modeType is equal        to MODE_TYPE_INTER or MODE_TYPE_INTRA.-   17. IBC mode may be allowed to use when modeType is equal to    MODE_TYPE_INTER    -   a. In one example, chroma IBC may be disallowed when modeType is        equal to MODE_TYPE_INTRA.    -   b. In one example, IBC mode may be allowed to use when modeType        is equal to MODE_TYPE_INTRA or MODE_TYPE_INTER.    -   c. In one example, IBC mode may be allowed to use regardless        what modeType is.    -   d. In one example, within one SCIPU, IBC and inter mode may be        both allowed.    -   e. In one example, the size of IBC chroma block may always        corresponds to the size of corresponding luma block.    -   f. In one example, when modeType is equal to MODE_TYPE_INTER and        coding unit size is 4×4 in luma, signaling of pred_mode_ibc_flag        may be skipped and pred_mode_ibc_flag may be inferred to be        equal to 1.-   18. Palette mode may be allowed to use when modeType is    MODE_TYPE_INTER    -   a. In one example, chroma palette may be disallowed when        modeType is MODE_TYPE_INTRA.    -   b. In one example, IBC mode may be allowed to use when modeType        is equal to MODE_TYPE_INTRA or MODE_TYPE_INTER.    -   c. In one example, IBC mode may be allowed to use regardless        what modeType is.    -   d. In one example, palette mode may be allowed to use when        modeType is equal to MODE_TYPE_INTRA or MODE_TYPE_INTER.    -   e. In one example, palette mode may be allowed to use regardless        what modeType is.    -   f. In one example, within one SCIPU, palette and inter mode may        be both allowed.    -   g. In one example, within one SCIPU, palette, IBC and inter mode        may be all allowed.    -   h. In one example, the size of palette chroma block may always        corresponds to the size of corresponding luma block.    -   i. In one example, when modeType is equal to MODE_TYPE_INTER and        coding unit size is 4×4 in luma, signaling of pred_mode_plt_flag        may be skipped and pred_mode_plt_flag may be inferred to be        equal to 1.    -   j. In one example, when modeType is equal to MODE_TYPE_INTER and        coding unit size is 4×4 in luma, one message may be sent to        indicated if the current prediction mode is of IBC or palette.    -   k. In one example, whether to enable/disable Palette mode may        depend on slice types and modeType.        -   i. In one example, for I slices with MODE_TYPE_INTRA,            Palette mode may be enabled.        -   ii. In one example, for P/B slices with MODE_TYPE_INTER,            Palette mode may be enabled.-   19. When palette mode is enabled, local dualtree may be disallowed.    -   a. In one example, when palette mode is enabled,        modeTypeCondition may be always set equal to 0.-   20. For small chroma blocks with width equal to M (e.g., M=2) or    height equal to N (e.g., N=2), allowed intra prediction modes may be    restricted to be different from those allowed for large chroma    blocks.    -   a. In one example, only a subset of intra prediction mode of        available chroma intra prediction modes may be used.    -   b. In one example, only INTRA_DC mode may be used.    -   c. In one example, only INTRA_PLANAR mode may be used.    -   d. In one example, only INTRA_ANGULAR18 mode may be used.    -   e. In one example, only INTRA_ANGULAR50 mode may be used.    -   f. In one example, CCLM modes may be disallowed.-   21. For small chroma blocks with width equal to M (e.g., M=2) or    height equal to N (e.g., N=2), transform types may be restricted to    be different from those allowed for large chroma blocks.    -   a. In one example, only transform skip may be used.    -   b. In one example, only one-dimensional transform may be used.    -   c. In one example, coding tools that support multiple types of        transforms are disallowed.        -   i. Alternatively, the signaling of coding tools that support            multiple types of transforms is omitted.-   22. CIIP may be considered as MODE_TYPE_INTRA.    -   a. In one example, CIIP mode may be allowed when dualtree        partitioning is used.        -   i. In one example, CIIP mode may be allowed when CU type is            of DUAL_TREEE_CHROMA.    -   b. Alternatively, CIIP may be considered as MODE_TYPE_INTER        -   i. In one example, when chroma block width is equal to M            (e.g., M=2), CIIP mode may be disallowed.        -   ii. In one example, when chroma block width is equal to M            (e.g., M=2), intra prediction modes for chroma in CIIP may            be restricted to simple intra prediction mode.            -   1. In one example, INTRA_DC may be used for chroma intra                prediction, when chroma block width is equal to M (e.g.,                M=2).            -   2. In one example, INTRA_ANGULAR18 may be used for                chroma intra prediction, when chroma block width is                equal to M (e.g., M=2).            -   3. In one example, INTRA_ANGULAR50 may be used for                chroma intra prediction, when chroma block width is                equal to M (e.g., M=2).        -   iii. In one example, intra prediction modes for chroma in            CIIP may be restricted to simple intra prediction mode.            -   1. In one example, INTRA_DC may be used for chroma intra                prediction.            -   2. In one example, INTRA_ANGULAR18 mode may be used for                chroma intra prediction.            -   3. In one example, INTRA_ANGULAR50 mode may be used for                chroma intra prediction.-   23. For above bullets, the variables M and/or N may be pre-defined    or signaled.    -   a. In one example, M and/or N may be further dependent on color        formats (e.g., 4:2:0, 4:2:2, 4:4:4).-   24. modeType may be extended to cover more types.    -   a. In one example, modeType may be MODE_TYPE_IBC. When modeType        is equal to MODE_TYPE_IBC, the prediction mode is inferred to be        IBC.        -   i. In one example, pred_mode_flag is not signaled in this            case.        -   ii. In one example, pred_mode_ibc_flag is not signaled in            this case.        -   iii. In one example, pred_mode_plt_flag is not signaled in            this case.    -   b. In one example, modeType may be MODE_TYPE_PALETTE. When        modeType is equal to MODE_TYPE_PALETTE, the prediction mode is        inferred to be Palette mode.        -   i. In one example, pred_mode_flag is not signaled in this            case.        -   ii. In one example, pred_mode_ibc_flag is not signaled in            this case.        -   iii. In one example, pred_mode_plt_flag is not signaled in            this case.    -   c. In one example, mode_constraint_flag may be replaced by an        index to tell which one of allowed modeTypes are used.-   25. In one example, whether QT split is allowed for a block with    dimensions W×H may depend on modeType combined with dimensions.    -   a. For example, if modeType is equal to MODE_TYPE_INTER and W is        equal to 8 and H is equal to 8, QT spit is disallowed.-   26. In one example, whether vertical TT split is allowed for a block    with dimensions W×H may depend on modeType combined with dimensions.    -   a. For example, if modeType is equal to MODE_TYPE_INTER and W is        equal to 16 and H is equal to 4, vertical TT spit is disallowed.-   27. In one example, whether horizontal TT split is allowed for a    block with dimensions W×H may depend on modeType combined with    dimensions.    -   a. For example, if modeType is equal to MODE_TYPE_INTER and W is        equal to 4 and H is equal to 16, horizontal TT spit is        disallowed.-   28. In one example, whether vertical BT split is allowed for a block    with dimensions W×H may depend on modeType combined with dimensions.    -   a. For example, if modeType is equal to MODE_TYPE_INTER and W is        equal to 8 and H is equal to 4, vertical BT spit is disallowed.-   29. In one example, whether horizontal TT split is allowed for a    block with dimensions W×H may depend on modeType combined with    dimensions.    -   a. For example, if modeType is equal to MODE_TYPE_INTER and W is        equal to 4 and H is equal to 8, horizontal BT spit is        disallowed.-   30. In one example, whether the prediction mode of a CU is inferred    by modeType may depend on color components and/or block dimensions    W×H.    -   a. For example, the prediction mode of a chroma CU is inferred        by modeType; but the prediction mode of a luma CU is signaled        instead of inferred by modeType.        -   i. For example, the prediction mode of a luma CU is signaled            instead of inferred by modeType if W>4 or H>4.-   31. When SCIPU is applied, whether to and/or how to signal the    information related to delta QP of a first component may depend on    the splitting way of the first component.    -   a. In one example, when SCIPU is applied, whether to and/or how        to signal the information related to delta QP of a first        component may depend on the splitting way of the first component        and decoupled from the splitting way of a second component.    -   b. In one example, the first component is luma and the second        component is chroma.    -   c. In one example, the first component is chroma and the second        component is luma.-   32. Any variable related to delta QP of a first component cannot be    modified during the decoding or parsing process of a second    component when dual tree and/or local dual tree coding structure is    applied.    -   a. In one example, the local dual tree coding structure may be        used according to SCIPU.    -   b. In one example, the first component is luma and the second        component is chroma.        -   i. The variable may be IsCuQpDeltaCoded.    -   c. In one example, the first component is chroma and the second        component is luma.        -   i. The variable may be IsCuChromaQpOffsetCoded.-   33. When SCIPU is applied, the information related to delta QP of a    component (such as luma or chroma) may be signaled at most once in a    specific region wherein the luma component and the chroma component    are required to share the same mode type (such as MODE_TYPE_INTER or    MODE_TYPE_INTRA).    -   a. In one example, the specific region is a regarded as a        quantization group.-   34. M×N chroma intra blocks with M as block width and N as block    height may be not allowed.    -   a. In one example, DC prediction may be used for M×N chroma        intra prediction, for example, M=2 chroma samples, N=8 and/or 16        and/or 32 chroma samples.        -   i. In one example, the reconstructed neighbor pixels may be            not used for DC prediction.        -   ii. In one example, the neighbor reference pixels may be set            equal to 1<<(bitDepth−1) for DC prediction.        -   iii. In one example, PDPC may be not applied for the DC            prediction.        -   iv. In one example, the DC mode information may be not coded            for the M×N chroma intra block but derived.    -   b. In one example, CCLM prediction may be used for M×N chroma        intra prediction, for example, M=2 chroma samples, N=8 and/or 16        and/or 32 chroma samples.        -   i. In one example, the reconstructed neighbor pixels may be            not used for CCLM prediction.        -   ii. In one example, for CCLM prediction predc=a*rec_(L)+b            that the chroma prediction value predc is derived from luma            reconstructed value rec_(L), the parameters a and b may be            initialed to default fixed values (such as a=0, b=512) at            the beginning of a video unit such as SPS/video parameter            set (VPS)/PPS/Picture/subpicture/Slice/Tile/Brick/CTU            row/CTU/virtual pipeline data unit (VPDU)/CU/PU/transform            unit (TU).            -   1. In one example, a first-in-first-out table may be                maintained on the fly to update the CCLM parameters a                and b.        -   iii. In one example, PDPC may be not applied for the CCLM            prediction.        -   iv. In one example, the CCLM mode information may be not            coded for M×N chroma intra block but derived.        -   v. Alternatively, the proposed methods may be applied to            other kinds of CCLM coded chroma blocks with width unequal            to M or height unequal to N.            -   1. In one example, the CCLM parameters of previously                coded blocks may be utilized for current block instead                of being derived based on reconstruction information of                current block's neighboring blocks.            -   2. In one example, the CCLM parameters may be stored in                a table and updated on-the-fly, such as using first in,                first out (FIFO).    -   c. In one example, M×N chroma intra blocks may be not allowed in        dual tree, for example, M=2 chroma samples, N=8 and/or 16 and/or        32 chroma samples.        -   i. In one example, when treeType is equal to            DUAL_TREE_CHROMA, X split may be disabled for a coding tree            node with dimension equal to (M*a)×(N*b), where M*a as the            width of the coding tree node in chroma samples, and N*b as            the height of the coding tree node in chroma samples.            -   1. In one example, X is vertical BT split, a=2, b=1            -   2. In one example, X is horizontal BT split, a=1, b=2            -   3. In one example, X is vertical TT split, a=4, b=1            -   4. In one example, X is horizontal TT split, a=1, b=4    -   d. In one example, M×N chroma intra blocks may be not allowed in        single tree, for example, M=2 chroma samples, N=8 and/or 16        and/or 32 chroma samples.        -   i. In one example, in single tree, X split may be disabled            for the chroma components of a coding tree node with            dimension equal to (M*a*subWidthC)×(N*b*subHeightC), where            M*a as the width of the coding tree node in luma samples,            N*b as the height of the coding tree node in luma samples,            and subWidthC and subHeightC as the chroma subsampling ratio            in width and height dimentions, e.g., subWidthC and            subHeightC are equal to 2 for 4:2:0 chroma format.            -   1. In one example, X=vertical BT split, a=2, b=1            -   2. In one example, X=vertical TT split, a=4, b=1            -   3. In one example, X=horizontal BT split, a=1, b=2            -   4. In one example, X=horizontal TT split, a=1, b=2            -   5. In one example, X=horizontal TT split, a=1, b=4            -   6. In one example, the non-split chroma block may be                with dimension equal to (M*a)×(N*d).            -   7. In one example, the non-split chroma block may be                determined as MODE_TYPE_INTRA and only intra prediction                (and/or IBC and/or PLT modes) may be allowed for this                chroma block.            -   8. In one example, the X split may be allowed for the                luma components of this coding tree node, e.g., the luma                coding tree node may be further split to multiple luma                child nodes, and each luma child nodes may be determined                to MODE_TYPE_INTER while only inter prediction (and/or                IBC mode) may be allowed.            -   9. Alternatively, the chroma component may be further                split along with the collocated luma component, but the                mode type may be equal to MODE_TYPE_INTER and only inter                prediction (and/or IBC mode) may be allowed.        -   ii. In one example, M×N chroma intra blocks may be not            allowed in CIIP.            -   1. In one example, CIIP may be not allowed for a coding                block with dimension equal to                (M*subWidthC)×(N*subHeightC) in luma samples.                -   a) When CIIP is not allowed, the associated syntax                    element such as CIIP flag may be not coded in the                    bitstream.            -   2. In one example, the chroma blending process in CIIP                may be only filled with the predictions from inter part.                -   a) In one example, only luma intra prediction may be                    applied to a CIIP-coded block, while the chroma                    intra prediction may be not applied to a CIIP-coded                    block with dimension equal to                    (M*subWidthC)×(N*subHeightC) in luma samples.            -   3. In one example, DC prediction may be used for M×N                chroma intra prediction for a CIIP block, as described                in bullet 34(a).            -   4. In one example, CCLM prediction may be used for M×N                chroma intra prediction for a CIIP block, as described                in bullet 34(b).                Relationship Between losslessSizeY and                maxCTB/maxTBsize/maxTS Size-   35. The maximum transform size may be signalled and/or inferred in    different ways for lossless (and/or near lossless coding) and lossy    coding.    -   a. In one example, the maximum transform size for lossless        and/or near lossless coding may be referred to as other terms        such as “maximum residue size” or “maximum representing size”        since no transform is involved. In this disclosure, it may be        referred as “maxLosslessTbSizeY”.    -   b. In one example, lossless coding for a block may be referred        to a cu_transquant_bypass_flag for that block is equal to 1.    -   c. In one example, near lossless coding for a block may be        referred to coding with a QP smaller than a given threshold.        -   i. In one example, the threshold may be indicated in            dependency parameter set (DPS)/VPS/SPS/PPS/Tile/Slice/Brick            header.    -   d. In one example, near lossless coding for a block may be        referred to coding with a QP smaller than a given threshold and        transform_skip_flag is equal to 1 for that block.        -   i. In one example, the threshold may be indicated in            DPS/VPS/SPS/PPS/Tile/Slice/Brick header.    -   e. A first maximum transform size for lossless and/or near        lossless coding (e.g., maxLosslessTbSizeY) may be set        conditioned on the a second maximum tranform size which may be        used for lossy coding, and/or maximum coding tree unit size,        and/or maximum transform skip size.    -   f. The max transform size for lossless and/or near lossless        coding may be signalled at video unit level such as a syntax        element (SE) at        SPS/VPS/PPS/Subpicture/Slice/Tile/Brick/CTU/VPDU.        -   i. In one example, the SE may be signalled depending on the            maximum CTB size (e.g., log 2_ctu_size_minus5, CtbSizeY, and            etc.)            -   1. For example, the flag may be signalled when log                2_ctu_size_minus5 is larger than N (such as N=0).        -   ii. In one example, the SE may be signalled depending on the            maximum transform size (e.g.,            sps_max_luma_transform_size_64_flag, MaxTbSize, and etc.)            -   1. For example, the SE may be signalled when                sps_max_luma_transform_size_64_flag is equal to M (such                as M=1).        -   iii. In one example, the SE may be signalled depending on            the maximum transform skip size (e.g., log            2_transform_skip_max_size_minus2, MaxTsSize, and etc.)            -   1. For example, the SE may be signalled when log                2_transform_skip_max_size_minus2 is larger than K (such                as K=3).        -   iv. In one example, a delta value between            log(maxLosslessTbSizeY) and X may be signalled.            -   1. For example, X may be equal to log 2_ctu_size_minus5            -   2. For example, X may be equal to                sps_max_luma_transform_size_64_flag            -   3. For example, X may be equal to log                2_transform_skip_max_size_minus2            -   4. For example, X may be equal to a fixed integer.            -   5. In one example, delta−K may be signalled, where K is                an integer such as 1.        -   v. In one example, a delta value between maxLosslessTbSizeY            and X may be signalled.            -   1. For example, X may be equal to CtbSizeY            -   2. For example, X may be equal to MaxTbSize            -   3. For example, X may be equal to MaxTsSize            -   4. For example, X may be equal to a fixed integer.            -   5. In one example, delta−K may be signalled, where K is                an integer such as 1.        -   vi. In one example, maxLosslessTbSizeY of a video unit (such            as a            sequence/picture/subpicture/slice/tile/CTU/VPDU/CU/PU/TU)            may be derived from the SE.        -   vii. The SE may be a flag.        -   viii. When the flag is not present, it may be inferred to be            equal to a postive integer N.    -   g. In one example, if lossless and/or nearlossless coding is        applied to a video unit (such as cu_transquant_bypass_flag is        equal to 1), the maximum transform size for the video unit may        be set equal to maxLosslessTbSizeY, other than maxTbSizeY.    -   h. Alternatively, the maximum transform size for lossless and/or        near lossless coding for a video unit (such as a        sequence/picture/subpicture/slice/tile/CTU/VPDU/CU/PU/TU) may be        derived instead of being signalled.        -   i. For example, it may set equal to a fixed integer value M            (such as M=32 in luma samples).        -   ii. For example, it may be set equal to a second maximum            tranform size which may be used for lossy coding        -   iii. For example, it may be set equal to the maximum coding            tree unit size,        -   iv. For example, it may be set equal to the VPDU size,        -   v. For example, it may be set equal to the maximum transform            skip block size.        -   vi. For example, it may be set equal to the maximum residue            coding block size.-   36. For a M×N residue block by lossless coding (and/or near lossless    coding), it may be divided into more than one smaller residue    sub-blocks depending on maxLosslessTbSizeY.    -   a. After the division, the width and height of all the        sub-blocks are no greater than maxLosslessTbSizeY.    -   b. In one example, it may be divided into sub-blocks in a        recursive way until the width and height of all the sub-blocks        are no greater than maxLosslessTbSizeY.

Deblocking Related

-   37. Palette mode may be enabled in MODE_TYPE_ALL or MODE_TYPE_INTRA,    but always disallowed in MODE_TYPE_INTER.-   38. Deblocking boundary strength (bS) for chroma components may be    set to 0 when one side is of IBC mode and the other side is of    Palette mode.    -   a. In one example, bS for chroma components, when        ChromaArrayType is not equal to 0, is set to 0 when one side is        of IBC mode and the other side is of Palette mode.

Minimal Allowed QP for Transform Skip Blocks Related

-   39. The syntax element, e.g. internal_minus_input_bit_depth shown in    JVET-R0045, from which input bit depth can be inferred may be    constrained according to a certain profile.    -   a. In one example, (QpPrimeTsMin−4)/6 may be constrained to be        within the range of [0, 2] in a 10-bit profile.    -   b. In one example, (QpPrimeTsMin−4)/6 may be constrained to be 0        in a 8-bit profile.    -   c. In one example, (QpPrimeTsMin−4)/6 may be constrained to be        within [0, K] in a (K+8)-bit profile.    -   d. In one example, (QpPrimeTsMin−4)/6 may be constrained to be        within [0, K] in a (K+8)-bit profile.-   40. The minimal allowed QP, e.g., QpPrimeTsMin, may be constrained    according to a certain profile.    -   a. In one example, (QpPrimeTsMin−4)/6 may be constrained to be        within the range of [0, 2] in a 10-bit profile.    -   b. In one example, (QpPrimeTsMin−4)/6 may be constrained to be 0        in a 8-bit profile.    -   c. In one example, (QpPrimeTsMin−4)/6 may be constrained to be        within [0, K] in a (K+8)-bit profile.    -   d. In one example, (QpPrimeTsMin−4)/6 may be constrained to be        within [0, K] in a (K+8)-bit profile.

5. EMBODIMENTS

Newly added parts are marked in

, and the deleted parts from VVC working draft are marked with doublebrackets (e.g., [[a]] denotes the deletion of the character “a”). Themodifications are based on the latest VVC working draft (JVET-O2001-v11)

5.1 an Example Embodiment #1

The embodiment below is about the constraints on small block partitionsand prediction modes are applied to 4:2:0 and 4:4:4 chromaformats only(not apply to 4:0:0 and 4:4:4 chromaformats).

7.4.9.4 Coding Tree Semantics

The variable modeTypeCondition is derived as follows:

-   -   If one of the following conditions is true, modeTypeCondition is        set equal to 0        -   slice_type==I and qtbtt_dual_tree_intra_flag is equal to 1

        -   modeTypeCurr is not equal to MODE_TYPE_ALL

        -   

        -       -   Otherwise, if one of the following conditions is true,        modeTypeCondition is set equal to 1        -   cbWidth*cbHeight is equal to 64 and split_qt_flag is equal            to 1        -   cbWidth*cbHeight is equal to 64 and            MttSplitMode[x0][y0][mttDepth] is equal to SPLIT_TT_HOR or            SPLIT_TT_VER        -   cbWidth*cbHeight is equal to 32 and            MttSplitMode[x0][y0][mttDepth] is equal to SPLIT_BT_HOR or            SPLIT_BT_VER    -   Otherwise, if one of the following conditions is true,        modeTypeCondition is set equal to 1+(slice_type !=I ? 1: 0)        -   cbWidth*cbHeight is equal to 64 and            MttSplitMode[x0][y0][mttDepth] is equal to SPLIT_BT_HOR or            SPLIT_BT_VER        -   cbWidth*cbHeight is equal to 128 and            MttSplitMode[x0][y0][mttDepth] is equal to SPLIT_TT_HOR or            SPLIT_TT_VER    -   Otherwise, modeTypeCondition is set equal to 0

5.2 an Example Embodiment #2

The embodiment below is about the signaling of Palette mode flag notdepend on the modeType.

7.3.8.5 Coding Unit Syntax

coding_unit( x0, y0, cbWidth, cbHeight, cqtDepth, treeType, modeType ) {Descriptor  chType = treeType = = DUAL_TREE_CHROMA? 1 : 0  if(slice_type != I | | sps_ibc_enabled_flag | | sps_palette_enabled_flag) {  if(   treeType   !=   DUAL_TREE_CHROMA   &&    !( ( ( cbWidth = = 4 &&cbHeight = = 4 ) | | modeType = = MODE_TYPE_INTRA                     )   && !sps_ibc_enabled_flag ) )    cu_skip_flag[ x0 ][ y0 ] ae(v)  if( cu_skip_flag[ x0 ][ y0 ] = = 0  &&   slice_type!=   I    && !(cbWidth = = 4 && cbHeight = = 4 ) && modeType = = MODE_TYPE_ALL )   pred_mode_flag ae(v)   if( ( ( slice_type = = I  &&  cu_skip_flag[ x0][ y0 ] = =0 ) | |     ( slice_type != I && ( CuPredMode[ chType ][ x0][ y0 ] != MODE_INTRA                        | |      (cbWidth == 4   &&   cbHeight = = 4   && cu_skip_flag[ x0 ][ y0 ]      = =      0) ) ) )     &&     cbWidth <= 64 && cbHeight <= 64 && modeType !=MODE_TYPE_INTER                     &&     sps_ibc_enabled_flag &&treeType != DUAL_TREE_CHROMA )     pred_mode_ibc_flag ae(v)   if( ( ( (slice_type = = I | | ( cbWidth = = 4 && cbHeight = = 4 ) | |sps_ibc_enabled_flag     )                 &&     CuPredMode[ x0 ][ y0]   = =   MODE_INTRA )   | |    ( slice_type != I && !( cbWidth = = 4 &&cbHeight = = 4 ) && !sps_ibc_enabled_flag    &&   CuPredMode[ x0 ][ y0] != MODE_INTRA ) )   && sps_palette_enabled_flag                    &&   cbWidth <=  64  &&  cbHeight <= 64  &&  && cu_skip_flag[ x0 ][ y0]     = =     0        [[&&    modeType != MODE_INTER ]])  pred_mode_plt_flag ae(v)

5.3 an Example Embodiment #3

The embodiment below is about the IBC prediction mode flag is inferreddepending on the CU SKIP flag and the mode Type.pred_mode_ibc_flag equal to 1 specifies that the current coding unit iscoded in IBC prediction mode. pred_mode_ibc_flag equal to 0 specifiesthat the current coding unit is not coded in IBC prediction mode.When pred_mode_ibc_flag is not present, it is inferred as follows:

-   -   If cu_skip_flag[x0][y0] is equal to 1, and cbWidth is equal to        4, and cbHeight is equal to 4, pred_mode_ibc_flag is inferred to        be equal 1.    -   Otherwise, if both cbWidth and cbHeight are equal to 128,        pred_mode_ibc_flag is inferred to be equal to 0.    -   [[Otherwise, if cu_skip_flag[x0][y0] is equal to 1, and modeType        is equal to MODE_TYPE_INTRA, pred_mode_ibc_flag is inferred to        be equal to 1.]]    -   Otherwise, if modeType is equal to MODE_TYPE_INTER,        pred_mode_ibc_flag is inferred to be equal to 0.    -   Otherwise, if treeType is equal to DUAL_TREE_CHROMA,        pred_mode_ibc_flag is inferred to be equal to 0.    -   Otherwise, pred_mode_ibc_flag is infered to be equal to the        value of sps_ibc_enabled_flag when decoding an I slice, and 0        when decoding a P or B slice, respectively.        When pred_mode_ibc_flag is equal to 1, the variable        CuPredMode[chType][x][y] is set to be equal to MODE_IBC for x=x0        . . . x0+cbWidth−1 and y=y0 . . . y0+cbHeight−1.

5.4 an Example Embodiment #4

The embodiment below is about the signaling of IBC prediction mode flagdepend on MODE TYPE INTRA, and/or IBC mode is allowed for luma blocksregardless of whether it is small block size.

7.3.8.5 Coding Unit Syntax

coding_unit( x0, y0, cbWidth, cbHeight, cqtDepth, treeType, modeType ) {Descriptor  chType = treeType = = DUAL_TREE_CHROMA? 1 : 0  if(slice_type != I | | sps_ibc_enabled_flag | | sps_palette_enabled_flag) {  if(   treeType   !=   DUAL_TREE_CHROMA    &&    !( ( ( cbWidth = = 4&& cbHeight = = 4 ) | | modeType = =MODE_TYPE_INTRA                       )     && !sps_ibc_enabled_flag ) )   cu_skip_flag[ x0 ][ y0 ] ae(v)   if( cu_skip_flag[ x0 ][ y0 ] == 0  &&  slice_type  !=  I    && !( cbWidth = = 4 && cbHeight = = 4 ) &&modeType = = MODE_TYPE_ALL )    pred_mode_flag ae(v)   if( ( (slice_type = = I  &&  cu_skip_flag[ x0 ][ y0 ] = =0 )  | |     (slice_type != I && ( CuPredMode[ chType ][ x0 ][ y0 ] != MODE_INTRA | | 

     ( cbWidth = = 4   &&   cbHeight = = 4   && cu_skip_flag[ x0 ][ y0]     = =     0 ) ) ) )       &&    cbWidth <= 64 && cbHeight <= 64 && modeType !=MODE_TYPE_INTER                     &&     sps_ibc_enabled_flag &&treeType != DUAL_TREE_CHROMA )     pred_mode_ibc_flag ae(v)

5.5 an Example Embodiment #5

The embodiment below is about applying different intra blocksconstraints for 4:2:0 and 4:2:2 color formats.

7.4.9.4 Coding Tree Semantics

The variable modeTypeCondition is derived as follows:

-   -   If one of the following conditions is true, modeTypeCondition is        set equal to 0        -   slice_type==I and qtbtt_dual_tree_intra_flag is equal to 1        -   modeTypeCurr is not equal to MODE_TYPE_ALL    -   Otherwise, if one of the following conditions is true,        modeTypeCondition is set equal to 1        -   cbWidth*cbHeight is equal to 64 and split_qt_flag is equal            to 1        -   cbWidth*cbHeight is equal to 64 and            MttSplitMode[x0][y0][mttDepth] is equal to SPLIT_TT_HOR or            SPLIT_TT_VER        -   cbWidth*cbHeight is equal to 32 and            MttSplitMode[x0][y0][mttDepth] is equal to SPLIT_BT_HOR or            SPLIT_BT_VER    -   Otherwise, if one of the following conditions is true,        modeTypeCondition is set equal to 1+(slice_type !=I ? 1: 0)        -   cbWidth*cbHeight is equal to 64 and            MttSplitMode[x0][y0][mttDepth] is equal to SPLIT_BT_HOR or            SPLIT_BT_VER

        -   cbWidth*cbHeight is equal to 128 and            MttSplitMode[x0][y0][mttDepth] is equal to SPLIT_TT_HOR or            SPLIT_TT_VER

        -   

        -   

        -   

        -       -   Otherwise, modeTypeCondition is set equal to 0

5.6 an Example Embodiment #6

The embodiment below is about disallowing 2×N chroma intra blocks insingle tree.

7.4.9.4 Coding Tree Semantics

The variable modeTypeCondition is derived as follows:

-   -   If one of the following conditions is true, modeTypeCondition is        set equal to 0        -   slice_type==I and qtbtt_dual_tree_intra_flag is equal to 1        -   modeTypeCurr is not equal to MODE_TYPE_ALL    -   Otherwise, if one of the following conditions is true,        modeTypeCondition is set equal to 1        -   cbWidth*cbHeight is equal to 64 and split_qt_flag is equal            to 1        -   cbWidth*cbHeight is equal to 64 and            MttSplitMode[x0][y0][mttDepth] is equal to SPLIT_TT_HOR or            SPLIT_TT_VER        -   cbWidth*cbHeight is equal to 32 and            MttSplitMode[x0][y0][mttDepth] is equal to SPLIT_BT_HOR or            SPLIT_BT_VER    -   Otherwise, if one of the following conditions is true,        modeTypeCondition is set equal to 1+(slice_type !=I ? 1: 0)        -   cbWidth*cbHeight is equal to 64 and            MttSplitMode[x0][y0][mttDepth] is equal to SPLIT_BT_HOR or            SPLIT_BT_VER

        -   cbWidth*cbHeight is equal to 128 and            MttSplitMode[x0][y0][mttDepth] is equal to SPLIT_TT_HOR or            SPLIT_TT_VER

        -   

        -       -   Otherwise, modeTypeCondition is set equal to 0

5.7 an Example Embodiment #7

The embodiment below is about disallowing 2×N chroma intra blocks indual tree.

6.4.2 Allowed Binary Split Process

The variable allowBtSplit is derived as follows:

-   -   If one or more of the following conditions are true,        allowBtSplit is set equal to FALSE:        -   cbSize is less than or equal to MinBtSizeY

        -   cbWidth is greater than maxBtSize

        -   cbHeight is greater than maxBtSize

        -   mttDepth is greater than or equal to maxMttDepth

        -   treeType is equal to DUAL_TREE_CHROMA and            (cbWidth/SubWidthC)*(cbHeight/SubHeightC) is less than or            equal to 16

        -   

        -   treeType is equal to DUAL_TREE_CHROMA and modeType is equal            to MODE_TYPE_INTRA

6.4.3 Allowed Ternary Split Process

The variable allowTtSplit is derived as follows:

-   -   If one or more of the following conditions are true,        allowTtSplit is set equal to FALSE:        -   cbSize is less than or equal to 2*MinTtSizeY

        -   cbWidth is greater than Min(MaxTbSizeY, maxTtSize)

        -   cbHeight is greater than Min(MaxTbSizeY, maxTtSize)

        -   mttDepth is greater than or equal to maxMttDepth

        -   x0+cbWidth is greater than pic_width_in_luma_samples

        -   y0+cbHeight is greater than pic_height_in_luma_samples

        -   treeType is equal to DUAL_TREE_CHROMA and            (cbWidth/SubWidthC)*(cbHeight/SubHeightC) is less than or            equal to 32

        -   

        -   treeType is equal to DUAL_TREE_CHROMA and modeType is equal            to MODE_TYPE_INTRA    -   Otherwise, allowTtSplit is set equal to TRUE.

5.8 an Example Embodiment #8

The embodiment below is about enabling MODE_IBC for SCIPU chroma blocks.

7.3.8.5 Coding Unit Syntax

coding_unit( x0, y0, cbWidth, cbHeight, cqtDepth, treeType, modeType ) {Descriptor  chType = treeType = = DUAL_TREE_CHROMA? 1 : 0  if(slice_type != I | | sps_ibc_enabled_flag | | sps_palette_enabled_flag) {  if(  treeType   !=   DUAL_TREE_CHROMA    &&    !( ( ( cbWidth = = && cbHeight = = 4 ) | | modeType = =MODE_TYPE_INTRA                      )     && !sps_ibc_enabled_flag ) )   cu_skip_flag[ x0 ][ y0 ] ae(v)   if( cu_skip_flag[ x0 ][ y0 ] == 0  &&  slice_type  !=  I    && !( cbWidth = = 4 && cbHeight = = 4) && modeType = = MODE_TYPE_ALL )    pred_mode_flag ae(v)   if( ( (slice_type = = I  &&  cu_skip_flag[ x0 ][ y0 ] = =0 )  | |    (slice_type != I && ( CuPredMode[ chType ][ x0 ][ y0 ] != MODE_INTRA | | 

    ( cbWidth = = 4   &&   cbHeight = = 4   && cu_skip_flag[ x0 ][ y0]     = =     0 ) ) ) )      &&   cbWidth <= 64 && cbHeight <= 64 && modeType !=MODE_TYPE_INTER                     &&    sps_ibc_enabled_flag 

 [[treeType != DUAL_TREE_CHROMA)]]    pred_mode_ibc_flag ae(v)

5.9 an Example Embodiment 99 on Disallowing Block Partition whenmodeType is MODE_TYPE_INTER (Solution 1)

6.4.2 Allowed Binary Split Process

The variable allowBtSplit is derived as follows:

-   -   If one or more of the following conditions are true,        allowBtSplit is set equal to FALSE:        -   cbSize is less than or equal to MinBtSizeY

        -   cbWidth is greater than maxBtSize

        -   cbHeight is greater than maxBtSize

        -   mttDepth is greater than or equal to maxMttDepth

        -   treeType is equal to DUAL_TREE_CHROMA and            (cbWidth/SubWidthC)*(cbHeight/SubHeightC) is less than or            equal to 16

        -   

        -   treeType is equal to DUAL_TREE_CHROMA and modeType is equal            to MODE_TYPE_INTRA

6.4.3 Allowed Ternary Split Process

The variable allowTtSplit is derived as follows:

-   -   If one or more of the following conditions are true,        allowTtSplit is set equal to FALSE:        -   cbSize is less than or equal to 2*MinTtSizeY

        -   cbWidth is greater than Min(MaxThSizeY, maxTtSize)

        -   cbHeight is greater than Min(MaxTbSizeY, maxTtSize)

        -   mttDepth is greater than or equal to maxMttDepth

        -   x0+cbWidth is greater than pic_width_in_luma_samples

        -   y0+cbHeight is greater than pic_height_in_luma_samples

        -   treeType is equal to DUAL_TREE_CHROMA and            (cbWidth/SubWidthC)*(cbHeight/SubHeightC) is less than or            equal to 32

        -   

        -   treeType is equal to DUAL_TREE_CHROMA and modeType is equal            to MODE_TYPE_INTRA    -   Otherwise, allowTtSplit is set equal to TRUE.

5.10 an Example Embodiment #10 on Disallowing Block Partition whenmodeType is MODE_TYPE_INTER (Solution 2)

6.4.2 Allowed Binary Split Process

The variable allowBtSplit is derived as follows:

-   -   If one or more of the following conditions are true,        allowBtSplit is set equal to FALSE:        -   cbSize is less than or equal to MinBtSizeY

        -   cbWidth is greater than maxBtSize

        -   cbHeight is greater than maxBtSize

        -   mttDepth is greater than or equal to maxMttDepth

        -   treeType is equal to DUAL_TREE_CHROMA and            (cbWidth/SubWidthC)*(cbHeight/SubHeightC) is less than or            equal to 16

        -   

        -   treeType is equal to DUAL_TREE_CHROMA and modeType is equal            to MODE_TYPE_INTRA

6.4.3 Allowed Ternary Split Process

The variable allowTtSplit is derived as follows:

-   -   If one or more of the following conditions are true,        allowTtSplit is set equal to FALSE:        -   cbSize is less than or equal to 2*MinTtSizeY

        -   cbWidth is greater than Min(MaxThSizeY, maxTtSize)

        -   cbHeight is greater than Min(MaxTbSizeY, maxTtSize)

        -   mttDepth is greater than or equal to maxMttDepth

        -   x0+cbWidth is greater than pic_width_in_luma_samples

        -   y0+cbHeight is greater than pic_height_in_luma_samples

        -   treeType is equal to DUAL_TREE_CHROMA and            (cbWidth/SubWidthC)*(cbHeight/SubHeightC) is less than or            equal to 32

        -   

        -   treeType is equal to DUAL_TREE_CHROMA and modeType is equal            to MODE_TYPE_INTRA    -   Otherwise, allowTtSplit is set equal to TRUE.

5.11 an Example Embodiment #11

The embodiment below is about the constraints further splitting of acoding tree when MODE_TYPE_INTER is derived.

7.3.8.4 Coding Tree Syntax

coding_tree( x0, y0, cbWidth, cbHeight, qgOnY, qgOnC, cbSubdiv,cqtDepth,     mttDepth, depthOffset, partIdx, treeTypeCurr, modeTypeCurr) { Descriptor . . .  treeType = ( modeType                   = =MODE_TYPE_INTRA ) ? DUAL_TREE_LUMA : treeTypeCurr  

  

 if( !split_qt_flag ) { . . .

5.12 an Example Embodiment #12

The embodiment below is about the constraints on small block partitionsand prediction modes are not applied when palette mode is enabled.

7.4.9.4 Coding Tree Semantics

The variable modeTypeCondition is derived as follows:

-   -   If one of the following conditions is true, modeTypeCondition is        set equal to 0        -   slice_type==I and qtbtt_dual_tree_intra_flag is equal to 1

        -   modeTypeCurr is not equal to MODE_TYPE_ALL

        -       -   Otherwise, if one of the following conditions is true,        modeTypeCondition is set equal to 1        -   cbWidth*cbHeight is equal to 64 and split_qt_flag is equal            to 1        -   cbWidth*cbHeight is equal to 64 and            MttSplitMode[x0][y0][mttDepth] is equal to SPLIT_TT_HOR or            SPLIT_TT_VER        -   cbWidth*cbHeight is equal to 32 and            MttSplitMode[x0][y0][mttDepth] is equal to SPLIT_BT_HOR or            SPLIT_BT_VER    -   Otherwise, if one of the following conditions is true, modeType        Condition is set equal to 1+(slice_type !=I ? 1: 0)        -   cbWidth*cbHeight is equal to 64 and            MttSplitMode[x0][y0][mttDepth] is equal to SPLIT_BT_HOR or            SPLIT_BT_VER        -   cbWidth*cbHeight is equal to 128 and            MttSplitMode[x0][y0][mttDepth] is equal to SPLIT_TT_HOR or            SPLIT_TT_VER    -   Otherwise, modeTypeCondition is set equal to 0

5.13 an Example Embodiment #13

The embodiment below is about the small chroma intra block constraintsfor 4:2:2 color formats.

7.4.9.4 Coding Tree Semantics

The variable modeTypeCondition is derived as follows:

-   -   If one of the following conditions is true, modeTypeCondition is        set equal to 0        -   slice_type==I and qtbtt_dual_tree_intra_flag is equal to 1        -   modeTypeCurr is not equal to MODE_TYPE_ALL    -   Otherwise, if one of the following conditions is true,        modeTypeCondition is set equal to 1        -   cbWidth*cbHeight is equal to 64 and split_qt_flag is equal            to 1        -   cbWidth*cbHeight is equal to 64 and            MttSplitMode[x0][y0][mttDepth] is equal to SPLIT_TT_HOR or            SPLIT_TT_VER        -   cbWidth*cbHeight is equal to 32 and            MttSplitMode[x0][y0][mttDepth] is equal to SPLIT_BT_HOR or            SPLIT_BT_VER    -   Otherwise, if        one of the following conditions is true, modeTypeCondition is        set equal to 1+(slice_type !=I ? 1: 0)        -   cbWidth*cbHeight is equal to 64 and            MttSplitMode[x0][y0][mttDepth] is equal to SPLIT_BT_HOR or            SPLIT_BT_VER        -   cbWidth*cbHeight is equal to 128 and            MttSplitMode[x0][y0][mttDepth] is equal to SPLIT_TT_HOR or            SPLIT_TT_VER    -   Otherwise, modeTypeCondition is set equal to 0

5.14 Example #1 of Delta QP Signaling in SCIPU

coding_tree( x0, y0, cbWidth, cbHeight, qgOnY, qgOnC, cbSubdiv,cqtDepth,     mttDepth, depthOffset, partIdx, treeTypeCurr, modeTypeCurr) { Descriptor  if( ( allowSplitBtVer | | allowSplitBtHor | |allowSplitTtVer | | allowSplitTtHor    |allowSplitQT                              )  &&(  x0  +  cbWidth  <=  pic_width_in_luma_samples    )   && (y0 +cbHeight <= pic_height_in_luma_samples ) )   split_cu_flag ae(v)  if(cu_qp_delta_enabled_flag && qgOnY && cbSubdiv <= cu_qp_delta_subdiv ) {  IsCuQpDeltaCoded = 0   CuQpDeltaVal = 0   CuQgTopLeftX = x0  CuQgTopLeftY = y0  }  if(   cu_chroma_qp_offset_enabledflag  &&  qgOnC      &&   cbSubdiv <= cu_chroma_qp_offset_subdiv )  IsCuChromaQpOffsetCoded = 0  if( split_cu_flag ) {   if( (allowSplitBtVer | | allowSplitBtHor | | allowSplitTtVer | |allowSplitTtHor ) &&     allowSplitQT )    split_qt_flag ae(v)   if(!split_qt_flag ) {    if(  (  allowSplitBtHor   ||   allowSplitTtHor  )  &&     ( allowSplitBtVer | | allowSplitTtVer ) )    mtt_split_cu_vertical_flag ae(v)   if( ( allowSplitBtVer    &&    allowSplitTtVer    &&mtt_split_cu_vertical_flag        )              | |    (  allowSplitBtHor     &&     allowSplitTtHor &&!mtt_split_cu_vertical_flag ) )     mtt_split_cu_binary_flag ae(v)   }  if( modeTypeCondition = = 1 )    modeType = MODE_TYPE_INTRA   else if(modeTypeCondition = = 2 ) {    mode_constraint_flag ae(v)  modeType =mode_constraint_flag ? MODE_TYPE_INTRA : MODE_TYPE_INTER   } else {   modeType = modeTypeCurr   }   treeType = (modeType                      = = MODE_TYPE_INTRA ) ? DUAL_TREE_LUMA :treeTypeCurr   if( !split_qt_flag ) {    if( MttSplitMode[ x0 ][ y0 ][mttDepth ] = = SPLIT_BT_VER ) {  depthOffset += ( x0 + cbWidth >pic_width_in_luma_samples ) ? 1 : 0     x1 = x0 + ( cbWidth / 2 )    coding_tree( x0, y0, cbWidth / 2, cbHeight, qgOnY, qgOnC, cbSubdiv +1,  cqtDepth, mttDepth + 1, depthOffset, 0, treeType, modeType )     if(x1 < pic_width_in_luma_samples )  coding_tree( x1, y0, cbWidth / 2,cbHeightY, qgOnY, qgOnC,   cbSubdiv + 1,  cqtDepth, mttDepth + 1,depthOffset, 1, treeType, modeType )    } else if( MttSplitMode[ x0 ][y0 ][ mttDepth ] = = SPLIT _BT HOR ) {  depthOffset += ( y0 + cbHeight >pic_height_in_luma_samples ) ? 1 : 0     y1 = y0 + ( cbHeight / 2 )    coding_tree( x0, y0, cbWidth, cbHeight / 2, qgOnY, qgOnC, cbSubdiv +1,  cqtDepth, mttDepth + 1, depthOffset, 0, treeType, modeType )     if(y1 < pic_height_in_luma_samples )  coding_tree( x0, y1, cbWidth,cbHeight / 2, qgOnY, qgOnC,   cbSubdiv + 1,  cqtDepth, mttDepth + 1,depthOffset, 1, treeType, modeType )    } else if( MttSplitMode[ x0 ] [y0 ] [ mttDepth ] = = SPLIT_TT_VER ) {     x1 = x0 + ( cbWidth / 4 )    x2 = x0 + ( 3 * cbWidth / 4 )     

 = qgOnY  &&  ( cbSubdiv + 2    <= cu_qp_delta_subdiv )     

 = qgOnC  &&  ( cbSubdiv + 2   <= cu_chroma_qp_offset_subdiv ) coding_tree( x0, y0, cbWidth / 4, cbHeight,

   cbSubdiv + 2,  cqtDepth, mttDepth + 1, depthOffset, 0, treeType,modeType )  coding_tree( x1, y0, cbWidth / 2, cbHeight,

,

,  cbSubdiv + 1,  cqtDepth, mttDepth + 1, depthOffset, 1, treeType,modeType )  coding_tree( x2, y0, cbWidth / 4, cbHeight,

,

,   cbSubdiv + 2,  cqtDepth, mttDepth + 1, depthOffset, 2, treeType,modeType )   } else { /* SPLIT_TT_HOR */    y1 = y0 + (cbHeight / 4 )   y2 = y0 + ( 3 * cbHeight / 4 )    

 =  qgOnY  &&  ( cbSubdiv + 2<= cu_qp_delta_subdiv )    

 =  qgOnC  &&  (  cbSubdiv + 2    <= cu_chroma_qp_offset_subdiv ) coding_tree( x0, y0, cbWidth, cbHeight / 4,

,

,  cbSubdiv + 2,  cqtDepth, mttDepth + 1, depthOffset, 0, treeType,modeType )  coding_tree( x0, y1, cbWidth, cbHeight / 2,

,

,  cbSubdiv + 1,  cqtDepth, mttDepth + 1, depthOffset, 1, treeType,modeType )  coding_tree( x0, y2, cbWidth, cbHeight / 4,

,

,  cbSubdiv + 2,  cqtDepth, mttDepth + 1, depthOffset, 2, treeType,modeType )    }   } else {    x1 = x0 + ( cbWidth / 2 )    y1 = y0 + (cbHeight / 2 )    coding_tree( x0, y0, cbWidth / 2, cbHeight / 2, qgOnY,qgOnC, cbSubdiv + 2,  cqtDepth + 1, 0, 0, 0, treeType, modeType )    if(x1 < pic_width_in_luma_samples )     coding_tree( x1, y0, cbWidth / 2,cbHeight / 2, qgOnY, qgOnC, cbSubdiv + 2,  cqtDepth + 1, 0, 0, 1,treeType, modeType )    if( y1 < pic_height_in_luma_samples )    coding_tree( x0, y1, cbWidth / 2, cbHeight / 2, qgOnY, qgOnC,cbSubdiv + 2,  cqtDepth + 1, 0, 0, 2, treeType, modeType )    if( y1 <pic_height_in_luma_samples   &&   x1  < pic_width_in_luma_samples )    coding_tree( x1, y1, cbWidth / 2, cbHeight / 2, qgOnY, qgOnC,cbSubdiv + 2,  cqtDepth + 1, 0, 0, 3, treeType, modeType )   }  if(  modeTypeCur = = MODE_TYPE_ALL && modeType = = MODE_TYPE_INTRA ) {   coding_tree( x0, y0, cbWidth, cbHeight, qgOnY, qgOnC, cbSubdiv,cqtDepth,        mttDepth,        0,        0  DUAL_TREE_CHROMA,modeType )   }  } else   coding_unit( x0, y0, cbWidth, cbHeight,cqtDepth, treeTypeCurr, modeTypeCurr ) }

5.15 Example #2 of Delta QP Signaling in SCIPU

Descriptor coding_tree( x0, y0, cbWidth, cbHeight, qgOnY, qgOnC,cbSubdiv, cqtDepth, mttDepth, depthOffset,      partIdx, treeTypeCurr,modeTypeCurr ) {  if( ( allowSplitBtVer ∥ allowSplitBtHor ∥allowSplitTtVer ∥ allowSplitTtHor ∥ allowSplitQT )    &&( x0 + cbWidth<= pic_width_in_luma_samples )    && (y0 + cbHeight <=pic_height_in_luma_samples ) )   split_cu_flag ae(v)  if(cu_qp_delta_enabled_flag && qgOnY && cbSubdiv <= cu_qp_delta_subdiv ) {  IsCuQpDeltaCoded = 0   CuQpDeltaVal = 0   CuQgTopLeftX = x0  CuQgTopLeftY = y0  }  if( cu_chroma_qp_offset_enabled_flag && qgOnC &&  cbSubdiv <= cu_chroma_qp_offset_subdiv )   IsCuChromaQpOffsetCoded = 0 if( split_cu_flag ) {   if( ( allowSplitBtVer ∥ allowSplitBtHor ∥allowSplitTtVer ∥ allowSplitTtHor ) &&     allowSplitQT )   split_qt_flag ae(v)   if( !split_qt_flag ) {    if( ( allowSplitBtHor∥ allowSplitTtHor ) &&     ( allowSplitBtVer ∥ allowSplitTtVer ) )    mtt_split_cu_vertical_flag ae(v)    if( ( allowSplitBtVer &&allowSplitTtVer && mtt_split_cu_vertical_flag ) ∥     ( allowSplitBtHor&& allowSplitTtHor && !mtt_split_cu_vertical_flag ) )    mtt_split_cu_binary_flag ae(v)   }   if( modeTypeCondition = = 1 )   modeType = MODE_TYPE_INTRA   else if( modeTypeCondition = = 2 ) {   mode_constraint_flag ae(v)  modeType = mode_constraint_flag ?MODE_TYPE_INTRA : MODE_TYPE_INTER   } else {    modeType = modeTypeCurr  }   treeType = ( modeType = = MODE_TYPE_INTRA ) ? DUAL_TREE_LUMA :treeTypeCurr   if( !split_qt_flag ) {    if( MttSplitMode[ x0 ][ y0 ][mttDepth ] = = SPLIT_BT_VER ) {  depthOffset += ( x0 + cbWidth >pic_width_in_luma_samples ) ? 1 : 0     x1 = x0 + ( cbWidth / 2 )    coding_tree( x0, y0, cbWidth / 2, cbHeight, qgOnY, qgOnC, cbSubdiv +1,  cqtDepth, mttDepth + 1, depthOffset, 0, treeType, modeType )     if(x1 < pic_width_in_luma_samples )  coding_tree( x1, y0, cbWidth / 2,cbHeightY, qgOnY, qgOnC, cbSubdiv + 1,  cqtDepth, mttDepth + 1,depthOffset, 1, treeType, modeType )    } else if( MttSplitMode[ x0 ][y0 ][ mttDepth ] = = SPLIT_BT_HOR ) {  depthOffset += ( y0 + cbHeight >pic_height_in_luma_samples ) ? 1 : 0     y1 = y0 + ( cbHeight / 2 )    coding_tree( x0, y0, cbWidth, cbHeight / 2, qgOnY, qgOnC, cbSubdiv +1,  cqtDepth, mttDepth + 1, depthOffset, 0, treeType, modeType )     if(y1 < pic_height_in_luma_samples )  coding_tree( x0, y1, cbWidth,cbHeight / 2, qgOnY, qgOnC, cbSubdiv + 1,  cqtDepth, mttDepth + 1,depthOffset, 1, treeType, modeType )    } else if( MttSplitMode[ x0 ][y0 ][ mttDepth ] = = SPLIT_TT_VER ) {     x1 = x0 + ( cbWidth / 4 )    x2 = x0 + ( 3 * cbWidth / 4 )     

 = qgOnY && ( cbSubdiv + 2 <= cu_qp_delta_subdiv )     

 = qgOnC && ( cbSubdiv + 2 <= cu_chroma_qp_offset_subdiv )  coding_tree(x0, y0, cbWidth / 4, cbHeight, 

 , 

 , cbSubdiv + 2,  cqtDepth, mttDepth + 1, depthOffset, 0, treeType,modeType )  coding_tree( x1, y0, cbWidth / 2, cbHeight, 

 , 

 cbSubdiv + 1,  cqtDepth, mttDepth + 1, depthOffset, 1, treeType,modeType )  coding_tree( x2, y0, cbWidth / 4, cbHeight, 

 , 

 cbSubdiv + 2,  cqtDepth, mttDepth + 1, depthOffset, 2, treeType,modeType )    } else { /* SPLIT_TT_HOR */     y1 = y0 + ( cbHeight / 4 )    y2 = y0 + ( 3 * cbHeight / 4 )     

 = qgOnY && ( cbSubdiv + 2 <= cu_qp_delta_subdiv )     

 = qgOnC && ( cbSubdiv + 2 <= cu_chroma_qp_offset_subdiv )  coding_tree(x0, y0, cbWidth, cbHeight / 4, 

 , 

 , cbSubdiv + 2,  cqtDepth, mttDepth + 1, depthOffset, 0, treeType,modeType )  coding_tree( x0, y1, cbWidth, cbHeight / 2, 

 , 

 , cbSubdiv + 1,  cqtDepth, mttDepth + 1, depthOffset, 1, treeType,modeType )  coding_tree( x0, y2, cbWidth, cbHeight / 4, 

 , 

 , cbSubdiv + 2,  cqtDepth, mttDepth + 1, depthOffset, 2, treeType,modeType )    }   } else {    x1 = x0 + ( cbWidth / 2 )    y1 = y0 + (cbHeight / 2 )    coding_tree( x0, y0, cbWidth / 2, cbHeight / 2, qgOnY,qgOnC, cbSubdiv + 2,  cqtDepth + 1, 0, 0, 0, treeType, modeType )    if(x1 < pic_width_in_luma_samples )     coding_tree( x1, y0, cbWidth / 2,cbHeight / 2, qgOnY, qgOnC, cbSubdiv + 2,  cqtDepth + 1, 0, 0, 1,treeType, modeType )    if( y1 < pic_height_in_luma_samples )    coding_tree( x0, y1, cbWidth / 2, cbHeight / 2, qgOnY, qgOnC,cbSubdiv + 2,   cqtDepth + 1, 0, 0, 2, treeType, modeType )    if( y1 <pic_height_in_luma_samples && x1 < pic_width_in_luma_samples )    coding_tree( x1, y1, cbWidth / 2, cbHeight / 2, qgOnY, qgOnC,cbSubdiv + 2,  cqtDepth + 1, 0, 0, 3, treeType, modeType )   }   if(modeTypeCur = = MODE_TYPE_ALL && modeType = = MODE_TYPE_INTRA ) {   coding_tree( x0, y0, cbWidth, cbHeight, qgOnY, 0, cbSubdiv, cqtDepth,mttDepth, 0, 0   DUAL_TREE_CHROMA, modeType )   }  } else   coding_unit(x0, y0, cbWidth, cbHeight, cqtDepth, treeTypeCurr, modeTypeCurr ) }

5.16 Example #3 of Delta QP Signaling in SCIPU

Descriptor coding_tree( x0, y0, cbWidth, cbHeight, qgOnY, qgOnC,cbSubdiv, cqtDepth, mttDepth, depthOffset,      partIdx, treeTypeCurr,modeTypeCurr ) {  if( ( allowSplitBtVer ∥ allowSplitBtHor ∥allowSplitTtVer ∥ allowSplitTtHor ∥ allowSplitQT )    &&( x0 + cbWidth<= pic_width_in_luma_samples )    && (y0 + cbHeight <=pic_height_in_luma_samples ) )   split_cu_flag ae(v)  if(cu_qp_delta_enabled_flag && qgOnY && cbSubdiv <= cu_qp_delta_subdiv 

 

 ) {   IsCuQpDeltaCoded = 0   CuQpDeltaVal = 0   CuQgTopLeftX = x0  CuQgTopLeftY = y0  }  if( cu_chroma_qp_offset_enabled_flag && qgOnC &&  cbSubdiv <= cu_chroma_qp_offset_subdiv && 

 )   IsCuChromaQpOffsetCoded = 0  if( split_cu_flag ) {   if( (allowSplitBtVer ∥ allowSplitBtHor ∥ allowSplitTtVer ∥ allowSplitTtHor )&&     allowSplitQT )    split_qt_flag ae(v)   if( !split_qt_flag ) {   if( ( allowSplitBtHor ∥ allowSplitTtHor ) &&     ( allowSplitBtVer ∥allowSplitTtVer ) )     mtt_split_cu_vertical_flag ae(v)    if( (allowSplitBtVer && allowSplitTtVer && mtt_split_cu_vertical_flag ) ∥    ( allowSplitBtHor && allowSplitTtHor && !mtt_split_cu_vertical_flag) )     mtt_split_cu_binary_flag ae(v)   }   if( modeTypeCondition = = 1)    modeType = MODE_TYPE_INTRA   else if( modeTypeCondition = = 2 ) {   mode_constraint_flag ae(v)  modeType = mode_constraint_flag ?MODE_TYPE_INTRA : MODE_TYPE_INTER   } else {    modeType = modeTypeCurr  }   treeType = ( modeType = = MODE_TYPE_INTRA ) ? DUAL_TREE_LUMA :treeTypeCurr   if( !split_qt_flag ) {    if( MttSplitMode[ x0 ][ y0 ][mttDepth ] = = SPLIT_BT_VER ) {  depthOffset += ( x0 + cbWidth >pic_width_in_luma_samples ) ? 1 : 0     x1 = x0 + ( cbWidth / 2 )    coding_tree( x0, y0, cbWidth / 2, cbHeight, qgOnY, qgOnC, cbSubdiv +1,  cqtDepth, mttDepth + 1, depthOffset, 0, treeType, modeType )     if(x1 < pic_width_in_luma_samples )  coding_tree( x1, y0, cbWidth / 2,cbHeightY, qgOnY, qgOnC, cbSubdiv + 1,  cqtDepth, mttDepth + 1,depthOffset, 1, treeType, modeType )    } else if( MttSplitMode[ x0 ][y0 ][ mttDepth ] = = SPLIT_BT_HOR ) {  depthOffset += ( y0 + cbHeight >pic_height_in_luma_samples ) ? 1 : 0     y1 = y0 + ( cbHeight / 2 )    coding_tree( x0, y0, cbWidth, cbHeight / 2, qgOnY, qgOnC, cbSubdiv +1,  cqtDepth, mttDepth + 1, depthOffset, 0, treeType, modeType )     if(y1 < pic_height_in_luma_samples )  coding_tree( x0, y1, cbWidth,cbHeight / 2, qgOnY, qgOnC, cbSubdiv + 1,  cqtDepth, mttDepth + 1,depthOffset, 1, treeType, modeType )    } else if( MttSplitMode[ x0 ][y0 ][ mttDepth ] = = SPLIT_TT_VER ) {     x1 = x0 + ( cbWidth / 4 )    x2 = x0 + ( 3 * cbWidth / 4 )     

 = qgOnY && ( cbSubdiv + 2 <= cu_qp_delta_subdiv )     

 

 

 <=

 

 )  coding_tree( x0, y0, cbWidth / 4, cbHeight, 

 , 

 , cbSubdiv + 2,  cqtDepth, mttDepth + 1, depthOffset, 0, treeType,modeType )  coding_tree( x1, y0, cbWidth / 2, cbHeight, 

 , 

 , cbSubdiv + 1,  cqtDepth, mttDepth + 1, depthOffset, 1, treeType,modeType )  coding_tree( x2, y0, cbWidth / 4, cbHeight, 

 , 

 , cbSubdiv + 2,  cqtDepth, mttDepth + 1, depthOffset, 2, treeType,modeType )    } else { /* SPLIT_TT_HOR */     y1 = y0 + ( cbHeight / 4 )    y2 = y0 + ( 3 * cbHeight / 4 )     

 = qgOnY && ( cbSubdiv + 2 <= cu_qp_delta_subdiv )     

 = qgOnC && ( cbSubdiv + 2 <= cu_chroma_qp_offset_subdiv )  coding_tree(x0, y0, cbWidth, cbHeight / 4, 

 , 

 , cbSubdiv + 2,  cqtDepth, mttDepth + 1, depthOffset, 0, treeType,modeType )  coding_tree( x0, y1, cbWidth, cbHeight / 2, 

 , 

 , cbSubdiv + 1,  cqtDepth, mttDepth + 1, depthOffset, 1, treeType,modeType )  coding_tree( x0, y2, cbWidth, cbHeight / 4, 

 , 

 , cbSubdiv + 2,  cqtDepth, mttDepth + 1, depthOffset, 2, treeType,modeType )    }   } else {    x1 = x0 + ( cbWidth / 2 )    y1 = y0 + (cbHeight / 2 )    coding_tree( x0, y0, cbWidth / 2, cbHeight / 2, qgOnY,qgOnC, cbSubdiv + 2,  cqtDepth + 1, 0, 0, 0, treeType, modeType )    if(x1 < pic_width_in_luma_samples )     coding_tree( x1, y0, cbWidth / 2,cbHeight / 2, qgOnY, qgOnC, cbSubdiv + 2,  cqtDepth + 1, 0, 0, 1,treeType, modeType )    if( y1 < pic_height_in_luma_samples )    coding_tree( x0, y1, cbWidth / 2, cbHeight / 2, qgOnY, qgOnC,cbSubdiv + 2,  cqtDepth + 1, 0, 0, 2, treeType, modeType )    if( y1 <pic_height_in_luma_samples && x1 < pic_width_in_luma_samples )    coding_tree( x1, y1, cbWidth / 2, cbHeight / 2, qgOnY, qgOnC,cbSubdiv + 2,  cqtDepth + 1, 0, 0, 3, treeType, modeType )   }   if(modeTypeCur = = MODE_TYPE_ALL && modeType = = MODE_TYPE_INTRA ) {   coding_tree( x0, y0, cbWidth, cbHeight, qgOnY, 

 , cbSubdiv, cqtDepth, mttDepth, 0, 0   DUAL_TREE_CHROMA, modeType )   } } else   coding_unit( x0, y0, cbWidth, cbHeight, cqtDepth, treeTypeCurr, modeTypeCurr ) }

5.17 Example #4 of Delta QP Signaling in SCIPU

Descriptor coding_tree( x0, y0, cbWidth, cbHeight, qgOnY, qgOnC,cbSubdiv, cqtDepth, mttDepth, depthOffset,      partIdx, treeTypeCurr,modeTypeCurr ) {  if( ( allowSplitBtVer ∥ allowSplitBtHor ∥allowSplitTtVer ∥ allowSplitTtHor ∥ allowSplitQT )    &&( x0 + cbWidth<= pic_width_in_luma_samples )    && (y0 + cbHeight <=pic_height_in_luma_samples ) )   split_cu_flag ae(v)  if(cu_qp_delta_enabled_flag && qgOnY && cbSubdiv <= cu_qp_delta_subdiv ) {  IsCuQpDeltaCoded = 0   CuQpDeltaVal = 0   CuQgTopLeftX = x0  CuQgTopLeftY = y0  }  if( cu_chroma_qp_offset_enabled_flag && qgOnC &&  cbSubdiv <= cu_chroma_qp_offset_subdiv )   IsCuChromaQpOffsetCoded = 0 if( split_cu_flag ) {   if( ( allowSplitBtVer ∥ allowSplitBtHor ∥allowSplitTtVer ∥ allowSplitTtHor ) &&     allowSplitQT )   split_qt_flag ae(v)   if( !split_qt_flag ) {    if( ( allowSplitBtHor∥ allowSplitTtHor ) &&     ( allowSplitBtVer ∥ allowSplitTtVer ) )    mtt_split_cu_vertical_flag ae(v)    if( ( allowSplitBtVer &&allowSplitTtVer && mtt_split_cu_vertical_flag ) ∥     ( allowSplitBtHor&& allowSplitTtHor && !mtt_split_cu_vertical_flag ) )    mtt_split_cu_binary_flag ae(v)  }  if( modeTypeCondition = = 1 )   modeType = MODE_TYPE_INTRA   else if( modeTypeCondition = = 2 ) {   mode_constraint_flag ae(v)  modeType = mode_constraint_flag ?MODE_TYPE_INTRA : MODE_TYPE_INTER   } else {    modeType = modeTypeCurr  }  

  

  treeType = ( modeType = = MODE_TYPE_INTRA ) ? DUAL_TREE_LUMA :treeTypeCurr   if( !split_qt_flag ) {    if( MttSplitMode[ x0 ][ y0 ][mttDepth ] = = SPLIT_BT_VER ) {  depthOffset += ( x0 + cbWidth >pic_width_in_luma_samples ) ? 1 : 0     x1 = x0 + ( cbWidth / 2 )    coding_tree( x0, y0, cbWidth / 2, cbHeight, qgOnY, qgOnC, cbSubdiv +1,  cqtDepth, mttDepth + 1, depthOffset, 0, treeType, modeType )     if(x1 < pic_width_in_luma_samples )  coding_tree( x1, y0, cbWidth / 2,cbHeightY, qgOnY, qgOnC, cbSubdiv + 1,  cqtDepth, mttDepth + 1,depthOffset, 1, treeType, modeType )    } else if( MttSplitMode[ x0 ][y0 ][ mttDepth ] = = SPLIT_BT_HOR ) {  depthOffset += ( y0 + cbHeight >pic_height_in_luma_samples ) ? 1 : 0     y1 = y0 + ( cbHeight / 2 )    coding_tree( x0, y0, cbWidth, cbHeight / 2, qgOnY, qgOnC, cbSubdiv +1,  cqtDepth, mttDepth + 1, depthOffset, 0, treeType, modeType )     if(y1 < pic_height_in_luma_samples )  coding_tree( x0, y1, cbWidth,cbHeight / 2, qgOnY, qgOnC, cbSubdiv + 1,  cqtDepth, mttDepth + 1,depthOffset, 1, treeType, modeType )    } else if( MttSplitMode[ x0 ][y0 ][ mttDepth ] = = SPLIT_TT_VER ) {     x1 = x0 + ( cbWidth / 4 )    x2 = x0 + ( 3 * cbWidth / 4 )     qgOnY = qgOnY && ( cbSubdiv + 2 <=cu_qp_delta_subdiv )     qgOnC = qgOnC && ( cbSubdiv + 2 <=cu_chroma_qp_offset_subdiv )     coding_tree( x0, y0, cbWidth / 4,cbHeight, qgOnY, qgOnC, cbSubdiv + 2,  cqtDepth, mttDepth + 1,depthOffset, 0, treeType, modeType )     coding_tree( x1, y0, cbWidth /2, cbHeight, qgOnY, qgOnC, cbSubdiv + 1,  cqtDepth, mttDepth + 1,depthOffset, 1, treeType, modeType )     coding_tree( x2, y0, cbWidth /4, cbHeight, qgOnY, qgOnC, cbSubdiv + 2,  cqtDepth, mttDepth + 1,depthOffset, 2, treeType, modeType )    } else { /* SPLIT_TT_HOR */    y1 = y0 + ( cbHeight / 4 )     y2 = y0 + ( 3 * cbHeight / 4 )    qgOnY = qgOnY && ( cbSubdiv + 2 <= cu_qp_delta_subdiv )     qgOnC =qgOnC && ( cbSubdiv + 2 <= cu_chroma_qp_offset_subdiv )     coding_tree(x0, y0, cbWidth, cbHeight / 4, qgOnY, qgOnC, cbSubdiv + 2,  cqtDepth,mttDepth + 1, depthOffset, 0, treeType, modeType )     coding_tree( x0,y1, cbWidth, cbHeight / 2, qgOnY, qgOnC, cbSubdiv + 1,  cqtDepth,mttDepth + 1, depthOffset, 1, treeType, modeType )     coding_tree( x0,y2, cbWidth, cbHeight / 4, qgOnY, qgOnC, cbSubdiv + 2,  cqtDepth,mttDepth + 1, depthOffset, 2, treeType, modeType )    }   } else {    x1= x0 + ( cbWidth / 2 )    y1 = y0 + ( cbHeight / 2 )    coding_tree( x0,y0, cbWidth / 2, cbHeight / 2, qgOnY, qgOnC, cbSubdiv + 2,  cqtDepth +1, 0, 0, 0, treeType, modeType )    if( x1 < pic_width_in_luma_samples )    coding_tree( x1, y0, cbWidth / 2, cbHeight / 2, qgOnY, qgOnC,cbSubdiv + 2,  cqtDepth + 1, 0, 0, 1, treeType, modeType )    if( y1 <pic_height_in_luma_samples )     coding_tree( x0, y1, cbWidth / 2,cbHeight / 2, qgOnY, qgOnC, cbSubdiv + 2,  cqtDepth + 1, 0, 0, 2,treeType, modeType )    if( y1 < pic_height_in_luma_samples && x1 <pic_width_in_luma_samples )     coding_tree( x1, y1, cbWidth / 2,cbHeight / 2, qgOnY, qgOnC, cbSubdiv + 2,  cqtDepth + 1, 0, 0, 3,treeType, modeType )   }   if( modeTypeCur = = MODE_TYPE_ALL && modeType= = MODE_TYPE_INTRA ) {    coding_tree( x0, y0, cbWidth, cbHeight,qgOnY, qgOnC, cbSubdiv, cqtDepth, mttDepth, 0, 0   DUAL_TREE_CHROMA,modeType )   }  } else   coding_unit( x0, y0, cbWidth, cbHeight,cqtDepth, treeTypeCurr, modeTypeCurr ) }

5.18 Example #14 of Disabling Wx Chroma Intra Blocks

6.4.2. Allowed Binary Split Process

The variable allowBtSplit is derived as follows:

-   -   If one or more of the following conditions are true,        allowBtSplit is set equal to FALSE:        -   cbSize is less than or equal to MinBtSizeY

        -   cbWidth is greater than maxBtSize

        -   cbHeight is greater than maxBtSize

        -   mttDepth is greater than or equal to maxMttDepth

        -   treeType is equal to DUAL_TREE_CHROMA and            (cbWidth/SubWidthC)*(cbHeight/SubHeightC) is less than or            equal to 16

        -   

        -   

        -   treeType is equal to DUAL_TREE_CHROMA and modeType is equal            to MODE_TYPE_INTRA

6.4.3. Allowed Ternary Split Process

The variable allowTtSplit is derived as follows:

-   -   If one or more of the following conditions are true,        allowTtSplit is set equal to FALSE:        -   cbSize is less than or equal to 2*MinTtSizeY

        -   cbWidth is greater than Min(MaxThSizeY, maxTtSize)

        -   cbHeight is greater than Min(MaxTbSizeY, maxTtSize)

        -   mttDepth is greater than or equal to maxMttDepth

        -   x0+cbWidth is greater than pic_width_in_luma_samples

        -   y0+cbHeight is greater than pic_height_in_luma_samples

        -   treeType is equal to DUAL_TREE_CHROMA and            (cbWidth/SubWidthC)*(cbHeight/SubHeightC) is less than or            equal to 32

        -   

        -   

        -   treeType is equal to DUAL_TREE_CHROMA and mode Type is equal            to MODE_TYPE_INTRA    -   Otherwise, allowTtSplit is set equal to TRUE.

7.4.9.4. Coding Tree Semantics

The variable modeTypeCondition is derived as follows:

-   -   If one of the following conditions is true, modeTypeCondition is        set equal to 0        -   slice_type==I and qtbtt_dual_tree_intra_flag is equal to 1        -   modeTypeCurr is not equal to MODE_TYPE_ALL    -   Otherwise, if one of the following conditions is true,        modeTypeCondition is set equal to 1        -   cbWidth*cbHeight is equal to 64 and split_qt_flag is equal            to 1        -   cbWidth*cbHeight is equal to 64 and            MttSplitMode[x0][y0][mttDepth] is equal to SPLIT_TT_HOR or            SPLIT_TT_VER        -   cbWidth*cbHeight is equal to 32 and            MttSplitMode[x0][y0][mttDepth] is equal to SPLIT_BT_HOR or            SPLIT_BT_VER    -   Otherwise, if one of the following conditions is true, modeType        Condition is set equal to 1+(slice_type !=I ? 1: 0)        -   cbWidth*cbHeight is equal to 64 and            MttSplitMode[x0][y0][mttDepth] is equal to SPLIT_BT_HOR or            SPLIT_BT_VER

        -   cbWidth*cbHeight is equal to 128 and            MttSplitMode[x0][y0][mttDepth] is equal to SPLIT_TT_HOR or            SPLIT_TT_VER

        -   

        -   

        -   

        -       -   Otherwise, modeTypeCondition is set equal to 0

7.4.9.7. Merge Data Semantics

ciip_flag[x0][y0] specifies whether the combined inter-picture merge andintra-picture prediction is applied for the current coding unit. Thearray indices x0, y0 specify the location (x0, y0) of the top-left lumasample of the considered coding block relative to the top-left lumasample of the picture.When ciip flag[x0][y0] is not present, it is inferred as follows:

-   -   If all the following conditions are true, ciip_flag[x0][y0] is        inferred to be equal to 1:        -   sps_ciip_enabled_flag is equal to 1.

        -   general_merge_flag[x0][y0] is equal to 1.

        -   merge_subblock_flag[x0][y0] is equal to 0.

        -   regular_merge_flag[x0][y0] is equal to 0.

        -   cbWidth is less than 128.

        -   cbHeight is less than 128.

        -   

        -   cbWidth*cbHeight is greater than or equal to 64.    -   Otherwise, ciip_flag[x0][y0] is inferred to be equal to 0.

7.3.8.7. Merge Data Syntax

Descriptor merge_data( x0, y0, cbWidth, cbHeight, chType ) {  if (CuPredMode[ chType ][ x0 ][ y0 ] = = MODE_IBC ) {   if(MaxNumIbcMergeCand > 1 )    merge_idx[ x0 ][ y0 ] ae(v)  } else {   if(MaxNumSubblockMergeCand > 0 && cbWidth >= 8 && cbHeight >= 8 )   merge_subblock_flag[ x0 ][ y0 ] ae(v)   if( merge_subblock_flag[ x0][ y0 ] = = 1 ) {    if( MaxNumSubblockMergeCand > 1 )    merge_subblock_idx[ x0 ][ y0 ] ae(v)   } else {    if( ( cbWidth *cbHeight ) >= 64 && ( (sps_ciip_enabled_flag &&     cu_skip_flag[ x0 ][y0 ] = = 0 && cbWidth < 128 && cbHeight < 128) ∥     (sps_triangle_enabled_flag && MaxNumTriangleMergeCand > 1 &&    slice_type = = B ) ) )     regular_merge_flag[ x0 ][ y0 ] ae(v)   if ( regular_merge_flag[ x0 ][ y0 ] = = 1 ){     if(sps_mmvd_enabled_flag )      mmvd_merge_flag[ x0 ][ y0 ] ae(v)     if(mmvd_merge_flag[ x0 ][ y0 ] = = 1 ) {      if( MaxNumMergeCand > 1 )      mmvd_cand_flag[ x0 ][ y0 ] ae(v)      mmvd_distance_idx[ x0 ][ y0] ae(v)      mmvd_direction_idx[ x0 ][ y0 ] ae(v)     } else {      if(MaxNumMergeCand > 1 )       merge_idx[ x0 ][ y0 ] ae(v)     }    } else{     if( sps_ciip_enabled_flag && sps_triangle_enabled_flag &&     MaxNumTriangleMergeCand > 1 && slice_type = = B &&     cu_skip_flag[ x0 ][ y0 ] = = 0 

 

     ( cbWidth * cbHeight ) >= 64 && cbWidth < 128 && cbHeight < 128 ) {     ciip_flag[ x0 ][ y0 ] ae(v)     if( ciip_flag[ x0 ][ y0 ] &&MaxNumMergeCand > 1 )      merge_idx[ x0 ][ y0 ] ae(v)     if(!ciip_flag[ x0 ][ y0 ] && MaxNumTriangleMergeCand > 1 ) {     merge_triangle_split_dir[ x0 ][ y0 ] ae(v)     merge_triangle_idx0[ x0 ][ y0 ] ae(v)      merge_triangle_idx1[ x0][ y0 ] ae(v)     }    }   }  } }

5.18 Example to Set Chroma Deblocking Boundary Strength to be 0

The following changes, newly added parts are marked in bold and Italicand the deleted parts are marked with double brackets (e.g., [[a]]denotes the deletion of the character “a”). The modifications are basedon JVET-Q2001-yE.

8.8.3.5 Derivation Process of Boundary Filtering Strength

For xD_(i) with i=0 . . . xN and yD_(j) with j=0 . . . yN, the followingapplies:

-   -   If edgeFlags [xD_(i)][yD_(j)] is equal to 0, the variable bS        [xD_(i)][yD_(j)] is set equal to 0.    -   Otherwise, the following applies:        -   The sample values p₀ and q₀ are derived as follows:            -   If edgeType is equal to EDGE_VER, p₀ is set equal to                recPicture[xCb+xD_(i)−1][yCb+yD_(j)] and q₀ is set equal                to recPicture[xCb+xD_(i)][yCb+yD_(j)].            -   Otherwise (edgeType is equal to EDGE_HOR), p₀ is set                equal to recPicture[xCb+xD_(i)][yCb+yD_(j)−1] and q₀ is                set equal to recPicture[xCb+xD_(i)][yCb+yD_(j)].        -   The variable bS[xD_(i)][yD_(j)] is derived as follows:            -   If cIdx is equal to 0 and both samples p₀ and q₀ are in                a coding block with intra_bdpcm_luma_flag equal to 1,                bS[xD_(i)][yD_(j)] is set equal to 0.            -   Otherwise, if cIdx is greater than 0 and both samples p₀                and q₀ are in a coding block with                intra_bdpcm_chroma_flag equal to 1, bS[xD_(i)][yD_(j)]                is set equal to 0.            -   Otherwise, if the sample p₀ or q₀ is in the coding block                of a coding unit coded with intra prediction mode,                bS[xD_(i)][yD_(j)] is set equal to 2.            -   Otherwise, if the block edge is also a coding block edge                and the sample p₀ or q₀ is in a coding block with                ciip_flag equal to 1, bS[xD_(i)][yD_(j)] is set equal to                2.            -   Otherwise, if the block edge is also a transform block                edge and the sample p₀ or q₀ is in a transform block                which contains one or more non-zero transform                coefficient levels, bS[xD_(i)][yD_(j)] is set equal to                1.            -   [[Otherwise, if the prediction mode of the coding                subblock containing the sample p0 is different from the                prediction mode of the coding subblock containing the                sample q0 (i.e. one of the coding subblock is coded in                IBC prediction mode and the other is coded in inter                prediction mode), bS[xDi][yDj] is set equal to 1.]]            -   Otherwise, if cIdx is equal to 0,                edgeFlags[xD_(i)][yD_(j)] is set equal to 2, and one or                more of the following conditions are true,                bS[xD_(i)][yD_(j)] is set equal to 1:                -   .                -   The coding subblock containing the sample p₀ and the                    coding subblock containing the sample q₀ are both                    coded in IBC prediction mode, and the absolute                    difference between the horizontal or vertical                    component of the block vectors used in the                    prediction of the two coding subblocks is greater                    than or equal to 8 in units of 1/16 luma samples.                -   For the prediction of the coding subblock containing                    the sample p₀ different reference pictures or a                    different number of motion vectors are used than for                    the prediction of the coding subblock containing the                    sample q₀.                -    NOTE 1—The determination of whether the reference                    pictures used for the two coding sublocks are the                    same or different is based only on which pictures                    are referenced, without regard to whether a                    prediction is formed using an index into reference                    picture list 0 or an index into reference picture                    list 1, and also without regard to whether the index                    position within a reference picture list is                    different.                -    NOTE 2—The number of motion vectors that are used                    for the prediction of a coding subblock with                    top-left sample covering (xSb, ySb), is equal to                    PredFlagL0[xSb][ySb]+PredFlagL1[xSb][ySb].                -   One motion vector is used to predict the coding                    subblock containing the sample p₀ and one motion                    vector is used to predict the coding subblock                    containing the sample q₀, and the absolute                    difference between the horizontal or vertical                    component of the motion vectors used is greater than                    or equal to 8 in units of 1/16 luma samples.                -   Two motion vectors and two different reference                    pictures are used to predict the coding subblock                    containing the sample p₀, two motion vectors for the                    same two reference pictures are used to predict the                    coding subblock containing the sample q₀ and the                    absolute difference between the horizontal or                    vertical component of the two motion vectors used in                    the prediction of the two coding subblocks for the                    same reference picture is greater than or equal to 8                    in units of 1/16 luma samples.                -   Two motion vectors for the same reference picture                    are used to predict the coding subblock containing                    the sample p₀, two motion vectors for the same                    reference picture are used to predict the coding                    subblock containing the sample q₀ and both of the                    following conditions are true:                -    The absolute difference between the horizontal or                    vertical component of list 0 motion vectors used in                    the prediction of the two coding subblocks is                    greater than or equal to 8 in 1/16 luma samples, or                    the absolute difference between the horizontal or                    vertical component of the list 1 motion vectors used                    in the prediction of the two coding subblocks is                    greater than or equal to 8 in units of 1/16 luma                    samples.                -    The absolute difference between the horizontal or                    vertical component of list 0 motion vector used in                    the prediction of the coding subblock containing the                    sample p₀ and the list 1 motion vector used in the                    prediction of the coding subblock containing the                    sample q₀ is greater than or equal to 8 in units of                    1/16 luma samples, or the absolute difference                    between the horizontal or vertical component of the                    list 1 motion vector used in the prediction of the                    coding subblock containing the sample p₀ and list 0                    motion vector used in the prediction of the coding                    subblock containing the sample q₀ is greater than or                    equal to 8 in units of 1/16 luma samples.            -   Otherwise, the variable bS[xD_(i)][yD_(j)] is set equal                to 0.

FIG. 17A is a block diagram of a video processing apparatus 1700. Theapparatus 1700 may be used to implement one or more of the methodsdescribed herein. The apparatus 1700 may be embodied in a smartphone,tablet, computer, Internet of Things (IoT) receiver, and so on. Theapparatus 1700 may include one or more processors 1702, one or morememories 1704 and video processing hardware 1706. The processor(s) 1702may be configured to implement one or more methods described in thepresent disclosure. The memory (memories) 1704 may be used for storingdata and code used for implementing the methods and techniques describedherein. The video processing hardware 1706 may be used to implement, inhardware circuitry, some techniques described in the present disclosure.

FIG. 17B is another example of a block diagram of a video processingsystem in which disclosed techniques may be implemented. FIG. 17B is ablock diagram showing an example video processing system 1710 in whichvarious techniques disclosed herein may be implemented. Variousimplementations may include some or all of the components of the system1710. The system 1710 may include input 1712 for receiving videocontent. The video content may be received in a raw or uncompressedformat, e.g., 8 or 10 bit multi-component pixel values, or may be in acompressed or encoded format. The input 1712 may represent a networkinterface, a peripheral bus interface, or a storage interface. Examplesof network interface include wired interfaces such as Ethernet, passiveoptical network (PON), etc. and wireless interfaces such as wirelessfidelity (Wi-Fi) or cellular interfaces.

The system 1710 may include a coding component 1714 that may implementthe various coding or encoding methods described in the presentdisclosure. The coding component 1714 may reduce the average bitrate ofvideo from the input 1712 to the output of the coding component 1714 toproduce a coded representation of the video. The coding techniques aretherefore sometimes called video compression or video transcodingtechniques. The output of the coding component 1714 may be eitherstored, or transmitted via a communication connected, as represented bythe component 1716. The stored or communicated bitstream (or coded)representation of the video received at the input 1712 may be used bythe component 1718 for generating pixel values or displayable video thatis sent to a display interface 1720. The process of generatinguser-viewable video from the bitstream representation is sometimescalled video decompression. Furthermore, while certain video processingoperations are referred to as “coding” operations or tools, it will beappreciated that the coding tools or operations are used at an encoderand corresponding decoding tools or operations that reverse the resultsof the coding will be performed by a decoder.

Examples of a peripheral bus interface or a display interface mayinclude universal serial bus (USB) or high definition multimediainterface (HDMI) or Displayport, and so on. Examples of storageinterfaces include serial advanced technology attachment (SATA),peripheral component interconnect (PCI), integrated drive electronics(IDE) interface, and the like. The techniques described in the presentdisclosure may be embodied in various electronic devices such as mobilephones, laptops, smartphones or other devices that are capable ofperforming digital data processing and/or video display.

FIG. 21 is a block diagram that illustrates an example video codingsystem 100 that may utilize the techniques of this disclosure.

As shown in FIG. 21 , video coding system 100 may include a sourcedevice 110 and a destination device 120. Source device 110 generatesencoded video data which may be referred to as a video encoding device.Destination device 120 may decode the encoded video data generated bysource device 110 which may be referred to as a video decoding device.

Source device 110 may include a video source 112, a video encoder 114,and an input/output (I/O) interface 116.

Video source 112 may include a source such as a video capture device, aninterface to receive video data from a video content provider, and/or acomputer graphics system for generating video data, or a combination ofsuch sources. The video data may comprise one or more pictures. Videoencoder 114 encodes the video data from video source 112 to generate abitstream. The bitstream may include a sequence of bits that form acoded representation of the video data. The bitstream may include codedpictures and associated data. The coded picture is a codedrepresentation of a picture. The associated data may include sequenceparameter sets, picture parameter sets, and other syntax structures. I/Ointerface 116 may include a modulator/demodulator (modem) and/or atransmitter. The encoded video data may be transmitted directly todestination device 120 via I/O interface 116 through network 130 a. Theencoded video data may also be stored onto a storage medium/server 130 bfor access by destination device 120.

Destination device 120 may include an I/O interface 126, a video decoder124, and a display device 122.

I/O interface 126 may include a receiver and/or a modem. I/O interface126 may acquire encoded video data from the source device 110 or thestorage medium/server 130 b. Video decoder 124 may decode the encodedvideo data. Display device 122 may display the decoded video data to auser. Display device 122 may be integrated with the destination device120, or may be external to destination device 120 which be configured tointerface with an external display device.

Video encoder 114 and video decoder 124 may operate according to a videocompression standard, such as the High Efficiency Video Coding (HEVC)standard, Versatile Video Coding (VVC) standard and other current and/orfurther standards.

FIG. 22 is a block diagram illustrating an example of video encoder 200,which may be video encoder 114 in the system 100 illustrated in FIG. 21.

Video encoder 200 may be configured to perform any or all of thetechniques of this disclosure. In the example of FIG. 22 , video encoder200 includes a plurality of functional components. The techniquesdescribed in this disclosure may be shared among the various componentsof video encoder 200. In some examples, a processor may be configured toperform any or all of the techniques described in this disclosure.

The functional components of video encoder 200 may include a partitionunit 201, a prediction unit 202 which may include a mode select unit203, a motion estimation unit 204, a motion compensation unit 205 and anintra prediction unit 206, a residual generation unit 207, a transformunit 208, a quantization unit 209, an inverse quantization unit 210, aninverse transform unit 211, a reconstruction unit 212, a buffer 213, andan entropy encoding unit 214.

In other examples, video encoder 200 may include more, fewer, ordifferent functional components. In an example, prediction unit 202 mayinclude an intra block copy (IBC) unit. The IBC unit may performprediction in an IBC mode in which at least one reference picture is apicture where the current video block is located.

Furthermore, some components, such as motion estimation unit 204 andmotion compensation unit 205 may be highly integrated, but arerepresented in the example of FIG. 22 separately for purposes ofexplanation.

Partition unit 201 may partition a picture into one or more videoblocks. Video encoder 200 and video decoder 300 may support variousvideo block sizes.

Mode select unit 203 may select one of the coding modes, intra or inter,e.g., based on error results, and provide the resulting intra- orinter-coded block to a residual generation unit 207 to generate residualblock data and to a reconstruction unit 212 to reconstruct the encodedblock for use as a reference picture. In some example, Mode select unit203 may select a combination of intra and inter prediction (CIIP) modein which the prediction is based on an inter prediction signal and anintra prediction signal. Mode select unit 203 may also select aresolution for a motion vector (e.g., a sub-pixel or integer pixelprecision) for the block in the case of inter-prediction.

To perform inter prediction on a current video block, motion estimationunit 204 may generate motion information for the current video block bycomparing one or more reference frames from buffer 213 to the currentvideo block. Motion compensation unit 205 may determine a predictedvideo block for the current video block based on the motion informationand decoded samples of pictures from buffer 213 other than the pictureassociated with the current video block.

Motion estimation unit 204 and motion compensation unit 205 may performdifferent operations for a current video block, for example, dependingon whether the current video block is in an I slice, a P slice, or a Bslice.

In some examples, motion estimation unit 204 may perform uni-directionalprediction for the current video block, and motion estimation unit 204may search reference pictures of list 0 or list 1 for a reference videoblock for the current video block. Motion estimation unit 204 may thengenerate a reference index that indicates the reference picture in list0 or list 1 that contains the reference video block and a motion vectorthat indicates a spatial displacement between the current video blockand the reference video block. Motion estimation unit 204 may output thereference index, a prediction direction indicator, and the motion vectoras the motion information of the current video block. Motioncompensation unit 205 may generate the predicted video block of thecurrent block based on the reference video block indicated by the motioninformation of the current video block.

In other examples, motion estimation unit 204 may perform bi-directionalprediction for the current video block, motion estimation unit 204 maysearch the reference pictures in list 0 for a reference video block forthe current video block and may also search the reference pictures inlist 1 for another reference video block for the current video block.Motion estimation unit 204 may then generate reference indexes thatindicate the reference pictures in list 0 and list 1 containing thereference video blocks and motion vectors that indicate spatialdisplacements between the reference video blocks and the current videoblock. Motion estimation unit 204 may output the reference indexes andthe motion vectors of the current video block as the motion informationof the current video block. Motion compensation unit 205 may generatethe predicted video block of the current video block based on thereference video blocks indicated by the motion information of thecurrent video block.

In some examples, motion estimation unit 204 may output a full set ofmotion information for decoding processing of a decoder.

In some examples, motion estimation unit 204 may not output a full setof motion information for the current video. Rather, motion estimationunit 204 may signal the motion information of the current video blockwith reference to the motion information of another video block. Forexample, motion estimation unit 204 may determine that the motioninformation of the current video block is sufficiently similar to themotion information of a neighboring video block.

In one example, motion estimation unit 204 may indicate, in a syntaxstructure associated with the current video block, a value thatindicates to the video decoder 300 that the current video block has thesame motion information as another video block.

In another example, motion estimation unit 204 may identify, in a syntaxstructure associated with the current video block, another video blockand a motion vector difference (MVD). The motion vector differenceindicates a difference between the motion vector of the current videoblock and the motion vector of the indicated video block. The videodecoder 300 may use the motion vector of the indicated video block andthe motion vector difference to determine the motion vector of thecurrent video block.

As discussed above, video encoder 200 may predictively signal the motionvector. Two examples of predictive signaling techniques that may beimplemented by video encoder 200 include advanced motion vectorprediction (AMVP) and merge mode signaling.

Intra prediction unit 206 may perform intra prediction on the currentvideo block. When intra prediction unit 206 performs intra prediction onthe current video block, intra prediction unit 206 may generateprediction data for the current video block based on decoded samples ofother video blocks in the same picture. The prediction data for thecurrent video block may include a predicted video block and varioussyntax elements.

Residual generation unit 207 may generate residual data for the currentvideo block by subtracting (e.g., indicated by the minus sign) thepredicted video block(s) of the current video block from the currentvideo block. The residual data of the current video block may includeresidual video blocks that correspond to different sample components ofthe samples in the current video block.

In other examples, there may be no residual data for the current videoblock for the current video block, for example in a skip mode, andresidual generation unit 207 may not perform the subtracting operation.

Transform processing unit 208 may generate one or more transformcoefficient video blocks for the current video block by applying one ormore transforms to a residual video block associated with the currentvideo block.

After transform processing unit 208 generates a transform coefficientvideo block associated with the current video block, quantization unit209 may quantize the transform coefficient video block associated withthe current video block based on one or more quantization parameter (QP)values associated with the current video block.

Inverse quantization unit 210 and inverse transform unit 211 may applyinverse quantization and inverse transforms to the transform coefficientvideo block, respectively, to reconstruct a residual video block fromthe transform coefficient video block. Reconstruction unit 212 may addthe reconstructed residual video block to corresponding samples from oneor more predicted video blocks generated by the prediction unit 202 toproduce a reconstructed video block associated with the current blockfor storage in the buffer 213.

After reconstruction unit 212 reconstructs the video block, loopfiltering operation may be performed reduce video blocking artifacts inthe video block.

Entropy encoding unit 214 may receive data from other functionalcomponents of the video encoder 200. When entropy encoding unit 214receives the data, entropy encoding unit 214 may perform one or moreentropy encoding operations to generate entropy encoded data and outputa bitstream that includes the entropy encoded data.

FIG. 23 is a block diagram illustrating an example of video decoder 300which may be video decoder 124 in the system 100 illustrated in FIG. 21.

The video decoder 300 may be configured to perform any or all of thetechniques of this disclosure. In the example of FIG. 23 , the videodecoder 300 includes a plurality of functional components. Thetechniques described in this disclosure may be shared among the variouscomponents of the video decoder 300. In some examples, a processor maybe configured to perform any or all of the techniques described in thisdisclosure.

In the example of FIG. 23 , video decoder 300 includes an entropydecoding unit 301, a motion compensation unit 302, an intra predictionunit 303, an inverse quantization unit 304, an inverse transformationunit 305, and a reconstruction unit 306 and a buffer 307. Video decoder300 may, in some examples, perform a decoding pass generally reciprocalto the encoding pass described with respect to video encoder 200 (e.g.,FIG. 22 ).

Entropy decoding unit 301 may retrieve an encoded bitstream. The encodedbitstream may include entropy coded video data (e.g., encoded blocks ofvideo data). Entropy decoding unit 301 may decode the entropy codedvideo data, and from the entropy decoded video data, motion compensationunit 302 may determine motion information including motion vectors,motion vector precision, reference picture list indexes, and othermotion information. Motion compensation unit 302 may, for example,determine such information by performing the AMVP and merge mode.

Motion compensation unit 302 may produce motion compensated blocks,possibly performing interpolation based on interpolation filters.Identifiers for interpolation filters to be used with sub-pixelprecision may be included in the syntax elements.

Motion compensation unit 302 may use interpolation filters as used byvideo encoder 20 during encoding of the video block to calculateinterpolated values for sub-integer pixels of a reference block. Motioncompensation unit 302 may determine the interpolation filters used byvideo encoder 200 according to received syntax information and use theinterpolation filters to produce predictive blocks.

Motion compensation unit 302 may use some of the syntax information todetermine sizes of blocks used to encode frame(s) and/or slice(s) of theencoded video sequence, partition information that describes how eachmacroblock of a picture of the encoded video sequence is partitioned,modes indicating how each partition is encoded, one or more referenceframes (and reference frame lists) for each inter-encoded block, andother information to decode the encoded video sequence.

Intra prediction unit 303 may use intra prediction modes for examplereceived in the bitstream to form a prediction block from spatiallyadjacent blocks. Inverse quantization unit 303 inverse quantizes, i.e.,de-quantizes, the quantized video block coefficients provided in thebitstream and decoded by entropy decoding unit 301. Inverse transformunit 303 applies an inverse transform.

Reconstruction unit 306 may sum the residual blocks with thecorresponding prediction blocks generated by motion compensation unit302 or intra-prediction unit 303 to form decoded blocks. If desired, adeblocking filter may also be applied to filter the decoded blocks inorder to remove blockiness artifacts. The decoded video blocks are thenstored in buffer 307, which provides reference blocks for subsequentmotion compensation.

FIG. 18 is a flowchart for a method 1800 of processing a video. Themethod 1800 includes parsing 1802, for a conversion between a videoregion of a video and a coded representation of the video region, thecoded representation according to a syntax rule that defines arelationship between a chroma block size and a color format of the videoregion; and performing (1804) the conversion by performing the parsingaccording to the syntax rule.

A listing of examples preferred by some embodiments is provided next. Inthe present disclosure, a video region may be a coding block or a sliceor a coding tree unit or a prediction block or a transform block.

The first set of clauses show example embodiments of techniquesdiscussed in the previous section. The following clauses may beimplemented together with additional techniques described in item 1 ofthe previous section.

1. A method of video processing, comprising: parsing, for a conversionbetween a video region of a video and a coded representation of thevideo region, the coded representation according to a syntax rule thatdefines a relationship between a chroma block size and a color format ofthe video region; and performing the conversion by performing theparsing according to the syntax rule.

2. The method of clause 1, wherein the color format is 4:4:4 and wherethe syntax rule specifies that the chroma block is subject to a samesize constraint as that for a luma blocks.

3. The method of clause 1, wherein the color format is 4:2:2 and wherethe syntax rule specifies that the chroma block is subject to a samesize constraint as that for 4:2:0 color format.

4. The method of any of clauses 1-3, wherein the syntax specifies that aprediction modes and small block partitions are used in a chroma-formatdependent manner.

5. The method of clause 1, wherein the syntax rule defines that asmallest allowed size feature is enabled for the conversion of the videoregion based on the color format of the video region.

The following clauses may be implemented together with additionaltechniques described in item 2 of the previous section.

6. A method of video processing, comprising: determining, based on aproperty of a video and a chroma format of the video, a coding mode of acoding tree node of the video; and performing a conversion between acoded representation of the video and a video block of the coding treenode using the determined coding mode.

7. The method of clause 6, wherein the coding mode is determined to beMODE_TYPE_ALL for the chroma format being 4:2:2, MODE_TYPE_INTRA orMODE_TYPE_INTER for the chroma format being 4:2:0 in case the propertyis:

i. the coding node is an M×N coding tree node with a horizontal binarytree split;

ii. the coding node is an M×N coding tree node with a vertical binarytree split;

iii. the coding node is an M×N coding tree node with a horizontalternary tree split; or

iv. the coding node is an M×N coding tree node with a vertical ternarytree split.

8. The method of clause 7, wherein M=8, or 16 or 32 and N=4 or 8 or 16.

The following clauses may be implemented together with additionaltechniques described in item 12 of the previous section.

9. A method of video processing, comprising: determining, based on arule, whether a certain size of chroma blocks is allowed in a videoregion of a video; and performing a conversion between the video regionand a coded representation of the video region based on the determining.

10. The method of clause 9, wherein the rule specifies that 2×N chromablocks are disallowed due to the video region including a dual treepartition.

11. The method of clause 9, wherein the rule specifies that 2N chromablocks are disallowed due to the video region including a single treepartition.

12. The method of clauses 10 or 11, wherein N<=64.

The following clauses may be implemented together with additionaltechniques described in items 13, 14 and 15 of the previous section.

13. A method of video processing, comprising: determining, based on arule that allows use of a coding mode for a video condition, that acoding mode is permitted for a video region; and performing a conversionbetween a coded representation of pixels in the video region and pixelsof the video region based on the determining.

14. The method of clause 13, wherein the video condition is block size,and wherein the rule allows use of intra block copy mode for small blocksizes of luma blocks.

15. The method of clause 14, wherein the small block sizes include 8×4,8×8, 16×4 or 4×N luma block sizes.

16. The method of clause 13, wherein the rule allows use of intra blockcopy mode for conversion of the video region using a MODE_TYPE_INTERmode of coding.

17. The method of clause 13, wherein the rule allows use of palettecoding mode for conversion of the video region using a MODE_TYPE_INTERmode of coding.

The following clauses may be implemented together with additionaltechniques described in items 16, 17, 18 of the previous section.

18. A method of video processing, comprising: performing a conversionbetween a video block of a video and a coded representation of the videoblock using a video coding mode, wherein a syntax element signaling thecoding mode is selectively included in the coded representation based ona rule.

19. The method of clause 18, wherein the video coding mode is an intrablock coding mode and wherein the rule specifies to use a type of thevideo coding mode to control inclusion of the syntax element in thecoded representation.

20. The method of clause 19, wherein the rule specifies explicitlysignaling a non-SKIP block.

21. The method of clause 18, wherein the rule specifies to implicitlysignal intra block copy flag based on a skip flag and a mode type of thevideo block.

22. The method of clause 18, wherein the coding mode is a palette codingmode and wherein the rule specifies to selectively include a palettecoding indicator based on mode type of the video block.

The following clauses may be implemented together with additionaltechniques described in item 21 of the previous section.

23. A method of video processing, comprising: determining, due to achroma block having a size less than a threshold size, that a transformtype used during a conversion between the chroma block and a codedrepresentation of the chroma block is different from a transform typeused for a corresponding luma block conversion; and performing theconversion based on the determining.

24. The method of clause 23, wherein the threshold size is M×N, whereinM is 2.

The following clauses may be implemented together with additionaltechniques described in item 22 of the previous section.

25. The method of any of clauses 1 to 24 wherein, the conversion uses acombined inter and intra prediction mode as a MODE_TYPE_INTRA mode.

26. The method of any of clauses 18 to 22, wherein the conversion uses acombined inter and intra prediction mode as a MODE_TYPE_INTER mode. Forexample, when considering CIIP as MODE_TYPE_INTER, methods described initem 14-17 in the previous section may be applied. Or when methodsdescribed in items 14-16 are applied, CIIP can be considered asMODE_TYPE_INTER.

The following clauses may be implemented together with additionaltechniques described in items 3-6 of the previous section.

27. A method of video processing, comprising: determining, whether asmallest chroma block rule is enforced during a conversion between acoded representation of a video region and pixel values of the videoregion, based on a coding condition of the video region; and performingthe conversion based on the determining.

28. The method of clause 17, wherein the coding condition comprises acolor format of the video region.

29. The method of clause 18, wherein the video region has a width of Mpixels and a height of N pixels, and wherein the coding conditionfurther depends on values of M and/or N.

30. The method of clause 29, wherein the smallest chroma block rule isenabled due to the video region having 4:2:2 color format and M*N=32 orM*N=64.

The following clauses may be implemented together with additionaltechniques described in items 7-11 of the previous section.

31. A method of video processing, comprising: determining, for aconversion between a coded representation of a video region in a 4:2:2format and pixel values of the video region, a mode type to be used forthe conversion based on whether a smallest chroma block rule is enabledfor the video region; and performing the conversion based on thedetermining.

32. The method of clause 31, wherein the mode type of the video regionis set to 1 due to the video region having 4:2:2 format and the smallestchroma block rule being enabled.

33. The method of clause 31, wherein the determining the mode typeincludes determining the mode type to be an INTRA type due to thesmallest chroma block rule being enabled for the video region.

34. The method of clause 31, wherein the determining the mode typeincludes determining that the mode type INTER is disabled due to thesmallest chroma block rule being enabled for the video region.

The following clauses may be implemented together with additionaltechniques described in items 7-11 of the previous section.

35. A method of video processing, comprising: determining, for aconversion between a coded representation of a video block and a videoblock of a video, whether block partitioning is allowed during theconversion, based on a mode type used during the conversion or adimension of the video block; and performing the conversion using thedetermining.

36. The method of clause 35, wherein the block portioning comprises abinary tree partitioning or a ternary tree partitioning.

37. The method of any of clauses, 35-36 wherein, in case that the modetype is INTER mode, the block partitioning is based on a restrictionrule that allows or disallows partition types.

The following clauses may be implemented together with additionaltechniques described in item 34 of the previous section.

38. A method of video processing, comprising: determining, for aconversion between a coded representation of a video segment of a videoand the video segment, to apply a special processing mode for a chromablock of size M×N, where M by N are integers; and performing theconversion based on the determining.

39. The method of clause 38, wherein the special processing modedisables use of chroma blocks during the conversion.

40. The method of clause 38, wherein the special processing mode uses DCprediction for an intra prediction of the chroma block.

41. The method of clause 38, wherein the special processing modeincludes using a cross-component linear model for predicting intracoefficients of the chroma block from corresponding downsampled lumacoefficients.

42. The method of any of clauses 38-41, wherein the special processingmode disables use of the chroma block due to the video segment using adual tree partitioning.

43. The method of any of clauses 38-41, wherein the special processingmode disables use of the chroma block due to the video segment using asingle tree partitioning.

44. The method of any of clauses 1 to 43, wherein the conversioncomprises encoding the video into the coded representation.

45. The method of any of clauses 1 to 43, wherein the conversioncomprises decoding the coded representation to generate pixel values ofthe video.

46. A video decoding apparatus comprising a processor configured toimplement a method recited in one or more of clauses 1 to 45.

47. A video encoding apparatus comprising a processor configured toimplement a method recited in one or more of clauses 1 to 45.

48. A computer program product having computer code stored thereon, thecode, when executed by a processor, causes the processor to implement amethod recited in any of clauses 1 to 45.

49. A method, apparatus or system described in the present disclosure.

A second set of clauses show example embodiments of techniques discussedin the previous section (e.g., items 37-40).

1. A method of video processing (e.g., method 2400 as shown in FIG.24A), comprising: performing 2402 a conversion between a video includinga video region and a bitstream of the video according to a rule; andwherein the rule specifies a relationship between enablement of apalette mode and a coding type of the video region.

2. The method of clause 1, wherein the rule specifies that the palettemode is enabled in case that the coding type is MODE_TYPE ALL thatallows an intra mode, a palette mode, and an intra block copy mode forthe conversion or MODE_TYPE_INTRA that allows use of an intra mode forthe conversion.

3. The method of clause 2, wherein the rule specifies that the palettemode is always disabled in case that the coding type is MODE_TYPE_INTERthat allows only an inter coding mode.

4. A method of video processing (e.g., method 2410 as shown in FIG.24B), comprising: performing 2412 a conversion between a video includinga first video region and a second video region and a bitstream of thevideo according to a rule; and wherein the rule specifies that aboundary strength (bs) of a deblocking filter for chroma components ofthe video is set to 0 in case that a first block is in an intra blockcopy mode and a second block is in a palette mode.

5. The method of clause 4, wherein the rule further specifies that theboundary strength is set to 0 in case that a variable related to achroma component in the video has a certain value.

6. The method of clause 5, wherein the certain value is not equal to 0.

7. A method of video processing (e.g., method 2420 as shown in FIG.24C), comprising: performing 2422 a conversion between a video and abitstream of the video according to a format rule, and wherein theformat rule specifies that a variable related to an input bit depth ofthe video is constrained according to a profile of the bitstream.

8. The method of clause 7, wherein the variable isinternal_minus_input_bit_depth.

9. The method of clause 7, wherein the format rule specifies that thevariable is constrained to be within a range of [0, 2] in case of a10-bit profile.

10. The method of clause 7, wherein the format rule specifies that thevariable is constrained to be 0 in case of a 8-bit profile.

11. The method of clause 7, wherein the format rule specifies that thevariable is constrained to be within a range of [0, K] in case of a(K+8) bit profile, whereby K is an integer greater than 0.

12. A method of video processing (e.g., method 2430 as shown in FIG.24D), comprising: performing 2432 a conversion between a video and abitstream of the video according to a format rule, and wherein theformat rule specifies that a variable indicating minimum allowedquantization parameter is constrained according to a profile of thebitstream.

13. The method of clause 12, wherein the variable is QpPrimeTsMin.

14. The method of clause 13, wherein the format rule specifies that(QpPrimeTsMin−4)/6 is constrained to be within a range of [0, 2] in caseof a 10-bit profile.

15. The method of clause 13, wherein the format rule specifies that(QpPrimeTsMin−4)/6 is constrained to be 0 in case of an 8-bit profile.

16. The method of clause 12, wherein the format rule specifies that(QpPrimeTsMin−4)/6 is constrained to be within a range of [0, K] in caseof a (K+8) bit profile, whereby K is an integer greater than 0.

17. The method of any of clauses 1 to 16, wherein the conversionincludes encoding the video into the bitstream.

18. The method of any of clauses 1 to 16, wherein the conversionincludes decoding the video from the bitstream.

19. The method of any of clauses 1 to 16, wherein the conversionincludes generating the bitstream from the video, and the method furthercomprises: storing the bitstream in a non-transitory computer-readablerecording medium.

20. A video processing apparatus comprising a processor configured toimplement a method recited in any one or more of clauses 1 to 19.

21. A method of storing a bitstream of a video, comprising, a methodrecited in any one of clauses 1 to 19, and further including storing thebitstream to a non-transitory computer-readable recording medium.

22. A computer readable medium storing program code that, when executed,causes a processor to implement a method recited in any one or more ofclauses 1 to 19.

23. A computer readable medium that stores a bitstream generatedaccording to any of the above described methods.

24. A video processing apparatus for storing a bitstream representation,wherein the video processing apparatus is configured to implement amethod recited in any one or more of clauses 1 to 19.

The disclosed and other solutions, examples, embodiments, modules andthe functional operations described in this disclosure can beimplemented in digital electronic circuitry, or in computer software,firmware, or hardware, including the structures disclosed in thisdisclosure and their structural equivalents, or in combinations of oneor more of them. The disclosed and other embodiments can be implementedas one or more computer program products, i.e., one or more modules ofcomputer program instructions encoded on a computer readable medium forexecution by, or to control the operation of, data processing apparatus.The computer readable medium can be a machine-readable storage device, amachine-readable storage substrate, a memory device, a composition ofmatter effecting a machine-readable propagated signal, or a combinationof one or more them. The term “data processing apparatus” encompassesall apparatus, devices, and machines for processing data, including byway of example a programmable processor, a computer, or multipleprocessors or computers. The apparatus can include, in addition tohardware, code that creates an execution environment for the computerprogram in question, e.g., code that constitutes processor firmware, aprotocol stack, a database management system, an operating system, or acombination of one or more of them. A propagated signal is anartificially generated signal, e.g., a machine-generated electrical,optical, or electromagnetic signal, that is generated to encodeinformation for transmission to suitable receiver apparatus.

A computer program (also known as a program, software, softwareapplication, script, or code) can be written in any form of programminglanguage, including compiled or interpreted languages, and it can bedeployed in any form, including as a stand-alone program or as a module,component, subroutine, or other unit suitable for use in a computingenvironment. A computer program does not necessarily correspond to afile in a file system. A program can be stored in a portion of a filethat holds other programs or data (e.g., one or more scripts stored in amarkup language document), in a single file dedicated to the program inquestion, or in multiple coordinated files (e.g., files that store oneor more modules, sub programs, or portions of code). A computer programcan be deployed to be executed on one computer or on multiple computersthat are located at one site or distributed across multiple sites andinterconnected by a communication network.

The processes and logic flows described in this disclosure can beperformed by one or more programmable processors executing one or morecomputer programs to perform functions by operating on input data andgenerating output. The processes and logic flows can also be performedby, and apparatus can also be implemented as, special purpose logiccircuitry, e.g., a field programmable gate array (FPGA) or anapplication specific integrated circuit (ASIC).

Processors suitable for the execution of a computer program include, byway of example, both general and special purpose microprocessors, andany one or more processors of any kind of digital computer. Generally, aprocessor will receive instructions and data from a read only memory ora random-access memory or both. The essential elements of a computer area processor for performing instructions and one or more memory devicesfor storing instructions and data. Generally, a computer will alsoinclude, or be operatively coupled to receive data from or transfer datato, or both, one or more mass storage devices for storing data, e.g.,magnetic, magneto optical disks, or optical disks. However, a computerneed not have such devices. Computer readable media suitable for storingcomputer program instructions and data include all forms of non-volatilememory, media and memory devices, including by way of examplesemiconductor memory devices, e.g., erasable programmable read-onlymemory (EPROM), electrically erasable programmable read-only memory(EEPROM), and flash memory devices; magnetic disks, e.g., internal harddisks or removable disks; magneto optical disks; and compact disc,read-only memory (CD ROM) and digital versatile disc read-only memory(DVD-ROM) disks. The processor and the memory can be supplemented by, orincorporated in, special purpose logic circuitry.

While the present disclosure contains many specifics, these should notbe construed as limitations on the scope of any subject matter or ofwhat may be claimed, but rather as descriptions of features that may bespecific to particular embodiments of particular techniques. Certainfeatures that are described in the present disclosure in the context ofseparate embodiments can also be implemented in combination in a singleembodiment. Conversely, various features that are described in thecontext of a single embodiment can also be implemented in multipleembodiments separately or in any suitable subcombination. Moreover,although features may be described above as acting in certaincombinations and even initially claimed as such, one or more featuresfrom a claimed combination can in some cases be excised from thecombination, and the claimed combination may be directed to asubcombination or variation of a subcombination.

Similarly, while operations are depicted in the drawings in a particularorder, this should not be understood as requiring that such operationsbe performed in the particular order shown or in sequential order, orthat all illustrated operations be performed, to achieve desirableresults. Moreover, the separation of various system components in theembodiments described in the present disclosure should not be understoodas requiring such separation in all embodiments.

Only a few implementations and examples are described and otherimplementations, enhancements and variations can be made based on whatis described and illustrated in the present disclosure.

What is claimed is:
 1. A method for processing video data, comprising:determining, for a conversion between a current video block of a videopicture of a video and a bitstream of the video, whether a first codingmode is applied to the current video block according to a first rule,wherein in the first coding mode, reconstructed samples are representedby a set of representative color values, and the set of representativecolor values comprises at least one of 1) palette predictors, 2) escapedsamples, or 3) palette information included in the bitstream; andperforming the conversion at least based on the determining, wherein thefirst rule specifies that the first coding mode is conditionally allowedto the current video block when the current video block has a mode typeof MODE_TYPE_ALL or a mode type of MODE_TYPE_INTRA, and that the firstcoding mode is disallowed to the current video block when the currentvideo block has a mode type of MODE_TYPE_INTER.
 2. The method of claim1, wherein the mode type of MODE_TYPE_ALL specifies that whether intramodes, an intra block copy mode, the first coding mode, and inter modesare allowed for video blocks inside a coding tree node comprising thecurrent video block, wherein the mode type of MODE_TYPE_INTRA specifiesthat whether only intra modes, the intra block copy mode, and the firstcoding mode are allowed for video blocks inside a coding tree nodecomprising the current video block, and wherein the mode type ofMODE_TYPE_INTER specifies that whether only inter modes are allowed forvideo blocks inside a coding tree node comprising the current videoblock.
 3. The method of claim 1, wherein a variable of QpPrimeTsMinwhich indicates a minimum allowed quantization parameter and isdetermined based on a value of a syntax element included in thebitstream is further applied to determine the reconstructed samples ofthe current video block, wherein (QpPrimeTsMin−4)/6 is constrained to bewithin [0, K], where K is a positive integer.
 4. The method of claim 1,wherein a syntax element indicating a bit depth of samples in the videopicture is included in the bitstream and is constrained to be within [0,2].
 5. The method of claim 1, wherein a reconstructed picture samplearray of the video picture is further obtained and a deblocking filterprocess is applied to at least one edge in the reconstructed picturesample array, wherein an array of boundary filtering strengths isderived for the deblocking filter process according to a second rulespecifying that bS[xDi][yDj] is equal to 0 when a set of conditions arenot satisfied, the reconstructed picture sample array is a reconstructedluma picture sample array, a variable related to an edge flag is notequal to 2, and two variables mapping to two samples have differentvalues, wherein bS[xDi][yDj] denotes an element in the array of boundaryfiltering strengths for xDi with i=0 . . . xN and yDj with j=0 . . . yN,wherein the two samples are samples of the reconstructed picture samplearray corresponding to bS[xDi][yDj], and wherein the two variablesindicate prediction modes of two video blocks in the reconstructedpicture sample array and containing the two samples, respectively, orthe two variables indicate prediction modes of two video subblocksdivided from one or more video blocks in the reconstructed picturesample array and containing the two samples, respectively.
 6. The methodof claim 5, wherein the second rule further specifies thatbS[xD_(i)][yD_(j)] is equal to 0 when the set of conditions are notsatisfied, the reconstructed picture sample array is a reconstructedchroma picture sample array and the two variables mapping to the twosamples have different values.
 7. The method of claim 5, wherein the setof conditions comprises that the two samples are in a video block with aciip_flag equal to
 1. 8. The method of claim 5, wherein the set ofconditions comprises that a prediction mode of a first sample located ina same video unit with one of the two samples is an intra mode.
 9. Themethod of claim 1, wherein a reconstructed chroma picture sample arrayof the video picture is further obtained and a deblocking filter processis applied to at least one edge in the reconstructed chroma picturesample array, wherein an array of boundary filtering strengths isderived for the deblocking filter process according to a third rulespecifying that bS[xDi][yDj] corresponding to two samples of thereconstructed chroma picture sample array is set equal to 0 when the twosamples locates at two sides of an edge and the two sides are coded withthe first coding mode and an intra block copy mode, respectively. 10.The method of claim 1, wherein a syntax element indicating a bit depthof samples in the video picture is included in the bitstream and isconstrained to be within [0, M] in a (M+8) bit profile, where M is apositive integer.
 11. The method of claim 1, wherein the conversionincludes encoding the video into the bitstream.
 12. The method of claim1, wherein the conversion includes decoding the video from thebitstream.
 13. An apparatus for processing video data comprising aprocessor and a non-transitory memory with instructions thereon, whereinthe instructions upon execution by the processor, cause the processorto: determine, for a conversion between a current video block of a videopicture of a video and a bitstream of the video, whether a first codingmode is applied to the current video block according to a first rule,wherein in the first coding mode, reconstructed samples are representedby a set of representative color values, and the set of representativecolor values comprises at least one of 1) palette predictors, 2) escapedsamples, or 3) palette information included in the bitstream; andperform the conversion at least based on the determination, wherein thefirst rule specifies that the first coding mode is conditionally allowedto the current video block when the current video block has a mode typeof MODE_TYPE_ALL or a mode type of MODE_TYPE_INTRA, and that the firstcoding mode is disallowed to the current video block when the currentvideo block has a mode type of MODE_TYPE_INTER.
 14. The apparatus ofclaim 13, wherein the mode type of MODE_TYPE_ALL specifies that whetherintra modes, an intra block copy mode, the first coding mode, and intermodes are allowed for video blocks inside a coding tree node comprisingthe current video block, wherein the mode type of MODE_TYPE_INTRAspecifies that whether only intra modes, the intra block copy mode, andthe first coding mode are allowed for video blocks inside a coding treenode comprising the current video block, and wherein the mode type ofMODE_TYPE_INTER specifies that whether only inter modes are allowed forvideo blocks inside a coding tree node comprising the current videoblock.
 15. The apparatus of claim 13, wherein a variable of QpPrimeTsMinwhich indicates a minimum allowed quantization parameter and isdetermined based on a value of a syntax element included in thebitstream is further applied to determine the reconstructed samples ofthe current video block, wherein (QpPrimeTsMin−4)/6 is constrained to bewithin [0, K], where K is a positive integer.
 16. The apparatus of claim13, wherein a syntax element indicating a bit depth of samples in thevideo picture is included in the bitstream and is constrained to bewithin [0, 2].
 17. The apparatus of claim 13, wherein a reconstructedpicture sample array of the video picture is further obtained and adeblocking filter process is applied to at least one edge in thereconstructed picture sample array, wherein an array of boundaryfiltering strengths is derived for the deblocking filter processaccording to a second rule specifying that bS[xDi][yDj] is equal to 0when a set of conditions are not satisfied, the reconstructed picturesample array is a reconstructed luma picture sample array, a variablerelated to an edge flag is not equal to 2, and two variables mapping totwo samples have different values, wherein bS[xDi][yDj] denotes anelement in the array of boundary filtering strengths for xDi with i=0 .. . xN and yDj with j=0 . . . yN, wherein the two samples are samples ofthe reconstructed picture sample array corresponding to bS[xDi][yDj],and wherein the two variables indicate prediction modes of two videoblocks in the reconstructed picture sample array and containing the twosamples, respectively, or the two variables indicate prediction modes oftwo video subblocks divided from one or more video blocks in thereconstructed picture sample array and containing the two samples,respectively.
 18. The apparatus of claim 17, wherein the second rulefurther specifies that bS[xDi][yDj] is equal to 0 when the set ofconditions are not satisfied, the reconstructed picture sample array isa reconstructed chroma picture sample array and the two variablesmapping to the two samples have different values.
 19. A non-transitorycomputer-readable storage medium storing instructions that cause aprocessor to: determine, for a conversion between a current video blockof a video picture of a video and a bitstream of the video, whether afirst coding mode is applied to the current video block according to afirst rule, wherein in the first coding mode, reconstructed samples arerepresented by a set of representative color values, and the set ofrepresentative color values comprises at least one of 1) palettepredictors, 2) escaped samples, or 3) palette information included inthe bitstream; and perform the conversion at least based on thedetermination, wherein the first rule specifies that the first codingmode is conditionally allowed to the current video block when thecurrent video block has a mode type of MODE_TYPE_ALL or MODE_TYPE_INTRA,and that the first coding mode is disallowed to the current video blockwhen the current video block has a mode type of MODE_TYPE_INTER.
 20. Anon-transitory computer-readable recording medium storing a bitstreamwhich is generated by a method performed by a video processingapparatus, wherein the method comprises: determining, for a currentvideo block of a video picture of a video, whether a first coding modeis applied to the current video block according to a first rule, whereinin the first coding mode, reconstructed samples are represented by a setof representative color values, and the set of representative colorvalues comprises at least one of 1) palette predictors, 2) escapedsamples, or 3) palette information included in the bitstream; andgenerating the bitstream at least based on the determining, wherein thefirst rule specifies that the first coding mode is conditionally allowedto the current video block when the current video block has a mode typeof MODE_TYPE_ALL or MODE_TYPE_INTRA, and that the first coding mode isdisallowed to the current video block when the current video block has amode type of MODE_TYPE_INTER.